# Category Archives: Outside Project

Learn about the natural world doing an investigation or activity

# OS11 Floating Hot Water on Cold Water

If you pour water into water, it mixes up and has more volume. That is what usually happens. But if you are really up to the challenge, you can make hot water sit on top of cold water.

Question: How can hot water be made to sit on cold water?

Materials:

3 Jars

Water

Ice

Food coloring

Microwave or stove

Eye dropper

Procedure:

Half fill a jar with water

Add ice until some ice remains floating in the water

Half fill another jar with water

Heat this water close to boiling in the microwave (use a pan on the stove)

Add a drop of food coloring

Sometimes, when you heat water on the stove, you can look down into the pan and see the water moving. These currents are in the jar of hot water and carry the food coloring around.

How does the food coloring spread through this water?

Stir to finish mixing the coloring into the water

Half fill a jar with ice cold water with no ice in it

This is the hard part: You will use the eye dropper to add the hot water to the jar of cold water. Do this by sliding the water down the side of the jar. Continue adding water until the hot layer is 1.5 cm thick.

The hot water tries to stay up on top of the cold water. Right underneath the hot water is an area cooling off with a layer warming up so some of the food coloring goes down into these layers creating the lighter colored layer.

Observe the hot water layer every fifteen minutes for an hour

Observations:

Describe how the food coloring moves through the hot water

Describe what the hot water layer does

At the start

In fifteen minutes

Cold water has currents in it like the hot water does. That lowest layer of food coloring is getting pulled into these currents.

In thirty minutes

In forty-five minutes

In an hour

Conclusions:

Note: Density is how much stuff is in a certain volume. Something with less density will float on top of something less dense.

Is hot water more or less dense than cold water? Why do you think so?

Is this difference very much? Why do you think so?

What happens to the temperature of the hot water over the hour?

What will happen to the density of the hot water over the hour?

What will happen to the food coloring over time? Why do you think so?

The hot water cools off. The cold water warms up. The water currents carry the food coloring around until all of the water turns blue. Some of the currents are still visible in the center.

What I Found Out:

The drop of food coloring split into many long streamers in the hot water. They slowly moved around the jar as they sank toward the bottom. The streamers spread out through the water.
The drops of hot water went into the cold water a little bit then rose to the top. The layer of hot water spread across the cold water. The color was darker on the top of the hot water layer.
I stopped adding hot water when my layer was 1.5 cm thick. Gradually a layer of lighter blue water spread under the hot layer. It got almost as thick as the hot layer started out. Streamers sank toward the bottom. A center core of blue went from the hot layer to the bottom. Then the blue spread all through the water.
The hot water must be less dense than the cold water because it stays on top. The densities must be very similar because I had to be so careful not to mix them when I put the hot water in and a layer at the edge does mix a little.
As the jar sits on the table, the hot water cools off. The cold water warms up. As they get closer together in temperature, their densities get closer and the hot and cold water mix. Then the food coloring will spread throughout the water.

# OS10 Water Balloon Pressure

Water shot out of a hole in a can in an arc to the ground. The greater the water pressure behind the hole, the longer the arc. As the pressure fell, the arc shrank. Shouldn’t a hole in a water balloon act the same way?

Question: What happens to water coming out of a hole in a water balloon?

Materials:

Balloon

Pin

Water faucet in a large sink or hose

Block to set the water balloon on

Procedure:

Blow the balloon up about half way

Hold the neck closed and push on the balloon

How does the air behave?

It is easier to put a single hole in a partially blown up balloon. If the balloon is blown up too much, it will break.

Make a pin hole about half way down the balloon

Let the air go out of the hole

How does the balloon change as the air goes out?

Slide the neck of the balloon over the end of the faucet or hose [wetting it first makes this easier]

Even if the mouth of the balloon is tight on the faucet, hold it on as you put water in the balloon.

Place the block so the balloon will sit on it as it fills up

Turn the water on slowly to fill the balloon

How does the water come out through the hole?

What happens to the hole?

Turn the water off when the balloon is about two thirds full

Observe how the water and the balloon act as the water goes out of the water balloon

Warning: Do NOT take the balloon off the faucet until almost all of the water is out of it‼!

Observations:

How does air behave

When you push on an air filled balloon

When the air comes out of a hole in the balloon

Describe how water acts as you fill the water balloon

Like the water from the hole in the can, water arcs out of the hole in the balloon

Describe what happens to the hole

Describe what happens as the water balloon empties

Describe what happens to the balloon as it fills and empties

Conclusions:

Why does putting pressure on one part of an air filled balloon make another part bulge?

What happens to the balloon as you put pressure inside of it?

Why does the water arc get thicker as more water goes into the balloon?

The balloon stretches out and has elastic energy adding pressure to the water in the balloon making the water arc much bigger than the one from the can.

Compare the water arcs from the cans to the one from the balloon.

Why does the water arc from the balloon last so long?

What I Found Out:

I had some big round balloons. It was easy to blow one up just a little and poke a pin hole in it.

The balloon fit on the faucet in my bathroom sink tightly. I turned the water on a little.

For a few seconds water dripped out of the hole and ran down the balloon. After that the water arced out of the balloon. The balloon got bigger and so did the arc. Then both stopped changing.

I turned the water on a little harder. The balloon got a little bigger. The arc had more water in it but didn’t seem any bigger.

A balloon stretches as it gets bigger. A letter written on a balloon gets bigger as a balloon gets bigger. The hole got bigger so more water could get out.

I turned the water on a little more. The balloon got bigger slowly. The arc straightened out and had more water in it.

Taking the mouth of the balloon off the faucet before the balloon is empty lets the water form a geyser out of the mouth. This is only fun if you are outside on a hot day.

My sink was far too small. When the balloon got about eight inches across, the arc shot out over the sink and onto the floor.

When the water ran out of the can, the arc quickly shrank. The arc of water out of the balloon stayed up for a long time.

When I was done, I took the balloon off the faucet. Water shot up out of the mouth of the balloon like a geyser.

Only air and gravity put pressure on the water arcing out of the can. The balloon put pressure on the water inside of it making the arc large for a longer time and shooting the water out of the mouth when I took it off the faucet.

# OS9 Changing Water Pressure

A column of water presses down on its base. Each cubic centimeter adds another gram of mass changing water pressure on the base. We saw how that works last week.

When the siphon moved water from one jar to another, the water ran slower as the jars were closer in height or the water level went down in the jar.

If you put a hole in a can, any water in the can will run out. What if there is more than one hole in the can? How will this affect how the water runs out of the can?

Question: How does changing water pressure affect how water flows?

Materials:

2 very large juice cans with the top removed or soda bottles with the tops cut off

1 soup can or jar to set the large cans or bottles on

Large tray [not needed if you do this outside]

Drill with a 1/8 inch bit [Help to drill some holes in the cans]

Ruler

Tape

4 Nickels

Procedure:

Drill three holes 0.5 cm from the bottom of one juice can or soda bottle spaced around the can

It is possible to use a nail if there is a tight board inside the can. Drilling a hole is much easier and makes a better hole.

Use the ruler to make a line down one side of the other can or soda bottle

Mark a point 0.5cm from the bottom, 5.5 cm up, 10.5 cm and 15.5 cm

The line of holes is supposed to be straight. Mine wavered a little as the drill slipped a bit on the can.

Drill holes at each mark

Put pieces of tape over the holes in the cans. Be sure these are tight.

The piece of tape needs to be tight over the hole. The ends are left loose for easy grabbing.

Put the can with three holes on the small can in the tray, a bathtub or ground outside

Fill the can with water to the top or a mark so you can fill the can the same each time

The can set well on the upside down jar. I didn’t get it put back exactly the same every time but couldn’t be too far off or the can would fall off. I filled the can to the rim each time.

Pull off one piece of tape and put a nickel where the water first hits the tray or ground

Measure how far the water went from the can

I measured from the jar each time as the centimeters started a little out on the ruler accounting for the overhang of the can.

Describe how the water stream acts as the can empties

Take off all the tape from the holes and dry the outside of the can thoroughly

Put one piece of tape over all three holes

Masking tape will not stick to a wet can. Again the ends are loose for easy grabbing. Each part over a hole is rubbed down tightly.

Set the can back on the prop can and fill it with water to the same place as before.

Pull the tape off quickly and put a nickel where one of the streams of water hits the tray or ground

Observe how the three streams of water act as the can empties out

Measure how far the water went from the can

Set this can aside and put pieces of tape over the holes

Put the other can on the prop can

If each tape is on tightly on a dry surface, the pieces will hold even through refilling.

Fill the can with water

Pull off the top tape piece and put a nickel where the water first hits the tray or ground

Measure how far the water went

Dry the outside of the can and replace the piece of tape

Fill the can

Pull the tape from the second hole down and put a nickel where the water first hits

Measure how far the water goes

Dry the outside of the can and replace the piece of tape

Fill the can with water

Pull the tape from the third hole down and put a nickel where the water first hits

This can behaved differently as the third hole stream went as far as the bottom hole in the first can.

Measure how far the water goes

Dry the outside of the can and replace the piece of tape

Fill the can with water

Pull the bottom piece of tape and put a nickel where the water first hits

Measure how far the water goes

Remove the pieces of tape and dry the outside of the can

It helps to hold the top of the can steady while pulling off the piece of tape.

Put one piece of tape covering all the holes

Set the can on the prop can

Fill the can with water

Pull the tape off quickly and place nickels where each stream of water hits the ground

[You may have to do this more than once to mark all the streams of water.]

Observe how the streams of water act

Measure how far the water goes for each hole

Observations:

1st can:

Distance the water goes with one hole open

Opening one hole on the bottom let the stream of water go out 26 cm. It stayed that far for a time as the water level dropped then slowly moved closer to the can until it finally dribbled out as the water level reached the hole.

How the water acts as the can empties

Distance the water goes with all three holes open

How the water acts as the can empties

2nd can:

Distance for top hole

How the water stream acts as the can empties

Distance for top hole with all holes open

Distance for second hole

Each time the stream of water is the longest at first and ends when the water level is the same as the hole.

How the water stream acts as the can empties

Distance for second hole with all holes open

Distance for third hole

How the water stream acts as the can empties

Distance for third hole with all holes open

Nickels work well for marking the distances. They are easy to see. They are heavy enough the water stream can’t wash them away.

Distance for fourth hole

How the water stream acts as the can empties

Distance for fourth hole with all holes open

How the water acts as the can empties

Conclusions:

For the first can, compare how the water stream with one hole open acts with how the three act with all the holes open.

The three streams went out a shorter distance than for a single hole. The water level l was the same over all three but the water had more than one way to go so less went out each hole.

For the first can, is the water pressure the same for all the holes? Why do you think so?

Is the rate of changing water pressure the same for all the holes? Why do you think so?

For the second can, is the water pressure the same for all the holes? Why do you think so?

Is the rate of changing water pressure the same for all the holes? Why do you think so?

Does where a hole is placed in a container affect how water empties out of the container?

All four distances were a little less than for single holes.

For the second can, compare how the water stream for the third hole acts with only that hole open to when all the holes are open.

Describe the changing water pressure as a can empties out.

Use the changing water pressure to explain how the water streams act as a can empties.

Do you think changing the sizes of the holes would change how the can empties?

Do you think making the holes different sizes would change how the can empties?

[You can try this and compare your ideas with what happens.]

What I Found Out:

My holes were a little high around the can. I put the tapes pieces over the three holes, set the can up and filled it with water. One tape dripped a little.

I steadied the can with one hand and pulled one piece of tape off. The stream of water went out. I marked it. It stayed going that far for a long time then gradually moved in until it was a dribble down the side of the can.

It was hard to dry the can until I got a towel. Then the tape went over all three holes. This time I steadied the can and jerked the tape off. Three streams of water shot out.

I marked the distance for one stream but the streams moved in faster than the single stream did. The three were soon dribbled down the side of the can.

For the single stream the distance was 26 cm. The distance with all three streams going was 23 cm.

The three streams acted much the same as the single stream except for being a little shorter and losing distance much faster. Since all the holes were the same distance up from the bottom of the can and the water was as deep over all the holes, they had the same water pressure on them. That made the rate of changing water pressure the same for all of them because the water level dropped the same over all of them.

Having the holes lined up from top to bottom of the can made the water act differently for each hole. The top hole water stream went the shortest distance, only 16 cm. The water stream shortened to a dribble very quickly.

The hole next down put out a longer stream, 24.5 cm. This stream lasted longer too.

The third hole had an even longer stream, 26 cm, and lasted longer too.

The fourth hole had the longest stream, 29 cm, and lasted the longest too.

The water level dropped very quickly with all four holes open. This made it hard to mark all four streams at one test.

The water streams acted the same as for the three holes. Changing water pressure caused the streams to get shorter until they dribbled as the water level dropped to the hole level.

These holes had different water pressure behind them as the water column over each was different.

When all four holes were opened up, the streams of water were shorter. The changing water pressure made the streams change distance quickly. I had to refill the can to get all of them marked.

Making all the holes larger would let the water out faster. I think the streams would be shorter too because making the hole at the end of a hose makes the water go farther.

If the holes were different sizes, the water would go out the larger holes faster so the changing water pressure would make the streams get shorter faster.

# OS8 Water Pressure

Perhaps you noticed the water flowing through the siphons slowed down as the top jar emptied out. Why would it do this?

Is this slowing related to less water in the jar so the mass is less making the water pressure on the siphon less?

When people go down to the bottom of the ocean, they go in small vehicles called bathyscaphes with very thick windows. Why is the glass so thick?

Question: What is water pressure?

Materials:

Scale

Thin plastic water bottle, empty

Water

Procedure:

Place the empty water bottle on the scale to mass it

Massing the empty bottle is important as you can then subtract this mass to find the mass of the water you add later on.

Take the bottle off the scale and pour 1 cm water in the bottle

Mass the bottle and water

Take the bottle off the scale

Pour 1 cm water in the bottle

The first centimeter is in the bottle. It distributes this mass over the bottom putting pressure on the scale.

Mass the bottle

Repeat this until the bottle is full or the scale can not have more mass on it

Observations:

Masses of bottle and water

Conclusions:

What happens to the mass of the bottle and water each time you add more water?

The bottle is filling up. Still all the mass of the water rests on the bottom of the bottle sitting on the scale.

If you were a bug standing on the bottom of the bottle, how much mass would be resting on your back when the first water landed in the bottle?

How much mass would be resting on your back when all the water is in the bottle?

Pressure is how much mass is resting on a certain area. As you add water mass to the bottle, what is happening to the water pressure on the bottom?

Water has a mass of 1 g for each cubic centimeter. If you were standing under a column of water a meter (100 cm) tall, how much mass or water pressure would be resting on you?

What if that column of water was 10 meters (1000 cm) tall?

Why are the windows of the bathyscaphes so thick?

What I Found Out:

Every time I added water to my bottle, the mass increased. Only 58.8 g of water would sit on my buggy back when the first centimeter of water arrived in my bottle. I’m glad I’m not a bug on the bottom of the bottle when the bottle was full because I would have 510.0 g of water sitting on my back.

The bottle is now full. All the mass is still resting on the bottom of the bottle giving that amount of pressure on the scale.

Since the area the water was resting on did not increase, the water column kept getting taller and heavier putting more pressure on that same area.

A column of water 100 cm tall would put 100 g of mass or pressure on my shoulder. But a column 1000 cm tall would put 1000 g of mass on my shoulder.

Bathyscaphes go to the bottom of the ocean, miles down. A mile is about 1.5 km or 1500 m or 150,000 cm which is 150,000 g or 150 kg of mass. [A kilogram is about 2.2 pounds so that is 330 pounds.] This would break a regular window. The thick glass is harder to break with the pressure.

# OS7 How A Siphon Works

Water runs uphill in a straw. Think about how you drank through a straw. First you pulled all the air out of the straw. Second the liquid replaced the air in the straw so you got a drink.

If a straw was open to the air, you couldn’t get a drink. You had to get and keep the air out of the straw.

What is a siphon? It is a long flexible tube used to move a liquid from one place to another.

Can a siphon make water run uphill like a straw can?

Question: How does a siphon work?

Materials:

2 Gallon Jars, clear

3 – 4 feet of clear plastic tubing (At least ¼ in. diameter, ½ in. is better)

1 ½ gallon water (Add a drop of food coloring to make it easier to see.)

Large measuring cup

Large pan or bowl to set a jar in in case the water spills

Chair or steps as high as a gallon jar

Note: It is easy to spill water in this project so working outside is a good idea.

Procedure:

Hold both ends of the tubing in one hand

Pour in water to half fill the tubing

Hold an end in each hand

Lift one end of the tubing and see what the water does (be careful not to spill)

Lower that end and lift the other end

Lower that end so the ends are even

Hold a thumb or finger over one end of the tubing

Lift one end of the tubing and observe the water

Lift the other end and observe the water

Even the ends of the tubing and block both ends with your thumbs or fingers

Lift one end of the tubing and observe the water

Lift the other end and observe the water

Fill one gallon jar almost full with water

Set the jar on the step or chair

The siphon tube is full of air when it’s put into the jars. The water can’t push the air out so no water flows through the tube.

Set the empty jar in the large pan on the floor next to the step or chair

Put the tubing into the empty jar

Pull enough tubing out to put into the jar of water all the way to the bottom

Observe what the water does

Take the tubing out of the water

Hold both ends of the tubing and pour water into it until the tubing is full

Once the air is out of the siphon tube, water runs quickly from the full jar into the empty jar.

Close off one end tightly with a thumb

Put the open end back into the empty jar

Put the closed end into the jar of water half way to the bottom

Release the end of the tubing and push it to the bottom of the jar

Observe what the water does

Especially when the full jar is on the low step, the siphon loop rises high above the jars. Yet the water still flows from the top jar into the bottom jar.

Pulling some of the tubing up from the bottom jar, make the loop between the two jars higher until the tubing only goes to the bottom of each jar

Observe what the water does

If the top jar is empty, switch the jars and start again

Put the full jar on a lower step or chair and do this again

Observe what the water does

It’s easy to see why water would move from a jar set higher than the lower jar yet water still moves from the full jar to the empty one when both are on the ground.

Put the two jars on the same level and start again

Observe what the water does

Observations:

Describe what the water in the tube does

With both ends open

With one end open

With both ends blocked

Describe what happens with the siphon tube

When put into the jars filled with air

When put in the jars filled with water

Describe what happens when the loop is lifted up

Describe how the siphon works with the jars closer together in height

When the siphon starts

When the loop is lifted

Describe what happens when the jars are beside each other

When the siphon starts

When the loop is lifted

Conclusions:

When both ends of the tubing are open, what can go in and out of the tubing besides water?

Is this still true when you block one or both ends?

How does this change how the water acts?

Why do you close one end of the filled tubing to put it into the jar of water?

Why does water move through the tubing from the full to the empty jar when it is filled with water but not when it is filled with air?

How does the movement of water change as the height of the loop changes?

Can the loop be too high for the water to keep moving?

How does the height difference between the jars affect how the water moves?

What causes the water to move from one jar to the other? Is this the same as how water comes up a straw?

Does water really move uphill by itself? Why do you think so?

The siphon continues to move water as long as the water is higher than the bottom jar until the level is so low air gets into the tube.

What I Found Out:

Making the water blue really helped me to see where the water was in the tube. I put enough in to half fill the tube.
When both ends of the tube were open, the water moved up and down as I moved the ends of the tube. The two surfaces stayed level no matter how fast or slowly I moved the tube ends.
Blocking one end of the tube changed things. The water moved only a little ways toward that end then stopped. When I lifted the blocked end up, the water didn’t move down very far until bubbles of air started moving up into that end.
Once both ends were blocked, air bubbles had to move from one end to the other to make the water levels change.
Air controls the water levels in the tube. When an end is not blocked, air can move in and out easily. Blocking one or both ends keeps the air at that level unless the open end is low enough for more air to move into the blocked end.
I used a step stool with two steps on it to set my jars on. The first time I set the full jar on the top step and the empty jar on the ground. One end of the tube went in the top jar. The other end went in the bottom jar. Nothing happened.
Leaving the two jars where they were, I took the tube out and poured water in it until it was full. Blocking one end keeps air from getting into the tube to push the water out. If the end in the lower end is open, air can bubble up into the tube before the other end gets into the top jar.
When the tube is full of air, the water doesn’t get pulled in just like when the one straw was outside the glass. A straw only works when all the air is pulled out. Having the tube full lets gravity pull the water down from the full jar to the empty jar. It works like a siphon. Raising the loop doesn’t stop the water from moving. It can slow the water down especially when the two jars were both on the ground.
The water moved differently when the top jar was placed on the different levels. Using the top step let the water move fast from the full to the empty jar. The top jar had only a little water left in it when air got into the tube and pushed the water out of the tube.
Using the lower step slowed the water down. It still moved from the top to the bottom jar, just not as fast. The top jar ended up almost empty at the end.

When both jars are on the ground, the siphon stops working when the water levels in both jars are the same leaving the tube filled with water.

Placing both jars on the ground changed everything. The water moved very slowly from the full jar to the empty one until the water level was the same in both. then it stopped. The tube was still full of water but it did not move. The water only moved when one jar had more water in it than the other, then ran downhill in a way to level it up.
Water does not move uphill on its own. It can appear to do so through the siphon loop but it is really ending up lower than at the beginning.

# OS6 Solving Straw Power

Water goes downhill because of gravity. Water defies gravity going up a straw. How?

Question: How does a straw work?
Materials:
2 clear straws
Clear glass of liquid (can be colored)
Procedure:
Put a finger over the end of a straw
Put the other end in the glass of liquid against the side of the glass

It’s hard to see but only a little bulge of liquid is at the bottom of the straw while the top is covered with a finger.

Observe what happens
Take your finger off the end of the straw
Observe what happens
Put your finger over the end of the straw and lift it out of the glass

Keeping the end of the straw blocked with a finger lets the column of liquid get lifted out.

Observe what the liquid does
Take your finger off the end of the straw (Hold it over the glass!)
Observe what the liquid does
Take a drink through the straw

Sarah finds drinking with one straw is easy. She pulls all the air out of the straw and juice rushes up fill he space.

Observe how you do this, how your mouth works
Put the second straw in the glass of liquid
Take a drink through both straws at once
Observe how you do this, how your mouth works
Take one of the straws out of the glass so one ends in teh glass and one out of the glass
Take a drink through both straws at once
Observe how you do this, how your mouth works
Observations:
Describe what was in the straw when your finger is on the top
Describe what is in the straw after removing your finger

When the straw is not blocked, liquid fills it up to the same level as in the glass.

Describe what the liquid does when you lift the straw
Describe what the liquid does when you remove your finger
Describe how you use a straw to take a drink

Two straws let Sarah drink her juice faster.

Describe how you use both straws to take a drink
Describe taking a drink with one straw in the glass, one out of the glass
Conclusions:
Why doesn’t liquid go into the straw when the top is blocked?
What happens when you take your finger off the straw?

Holding the filled straw over the table and taking the finger off is a way to make a big mess. Air rushes in and pushes the water out.

Why doesn’t air keep you from taking a drink with a straw?
Why can’t you take a drink through two straws when one is outside the glass?

What I Found Out:

I found two large diameter straws to use. For the first parts of the project I used water with a little blue food coloring. One drop was too much and I kept diluting itt until the water was light blue.

First I held a finger on the top of the straw and pushed it into the water. No water went into it. A small bulge was visible at the bottom.

Air filled the tube. When my finger was on top and water on the bottom, the air couldn’t go in or out. It kept the water out as there wasn’t room for both. As soon as the air could get out, it did letting the water fill the tube.

As soon as I took my finger off the top, water rushed in so the level inside and outside of the straw was the same. I put my finger back on top and lifted it out of the water. The water inside lifted up too and didn’t fall out until I took my finger off the top.

This time the water was trapped inside and kept the air out. Once air could get inside, the water left.

My friend Sarah Brown helped me with the rest of the project as it is difficult to drink through a straw and take pictures of me doing it at the same time.

When Sarah used one straw, she pulled all the air out of it and juice rushed in to fill it up. Two straws worked the same way only doubling the amount of juice Sarah could drink.

Sarah is trying to get a drink of juice. Air rushes in the straw on the outside replacing all the air she pulls out of the other straw so the juice can’t get into the straw.

Everything changed when one straw was in the juice and one was outside the glass. Now Sarah tried to pull all the air out of the straw but more air kept coming back. No juice would get pulled up.

# OS5 Float a Jar

Some things float. Some things sink. Some are in between. Why?

Often heavier things sink and lighter ones float. Can mass be the reason?

Question: Why do some things float and others sink?

Materials:

Big bucket of water

Small jar with lid

Scale

Procedure:

Put the lid on the jar tightly

Measure the jar’s height and diameter in centimeters

Mass the empty jar in grams.

Mass the jar in grams

Float the jar in the bucket of water

The empty jar floats high in the bucket of water.

Take the jar out of the water

Pour about 1.5 cm water into the jar

Put the lid on tightly

Mass the jar and water

Each addition of water increases the mass of the jar and increases its density.

Float the jar in the water

Describe how well the jar floats

Add another 1.5 cm water to the jar, mass it and float it

Continue to do this until the jar sinks

Observations:

Jar measurements:

Height:

Diameter ( biggest distance across)

Masses:

Empty jar:

How well it floated

Jar with 1.5 cm water:

How well it floated

The water in the jar tends to push the bottom into the water. It definitely doesn’t float as well as the empty jar.

Jar with 3 cm water:

How well it floated

Jar with 4.5 cm water

How well it floated

Jar with 6 cm water:

How well it floated

Jar with 7.5 cm water:

How well it floated

Jar with 9 cm water:

How well it floated

Analysis:
Calculate the volume of the jar (volume = πrrh where π is 3.14, r is half the diameter and squared, h is height)
Density is how much stuff is in a certain space. Calculate the density of the empty jar by dividing its mass by its volume. The units will be grams/cc or cubic centimeter.
Calculate the density of the jar with each addition of water.
There is another way you can use if your jar is not very square like mine with the top and bottom tapering. Fill your jar to the very brim with water and put the lid on tightly. Mass it. Subtract the mass of the empty jar. Water is supposed to have 1 gram equal to 1 cc so the answer should be close to the volume of the jar.
Conclusions:
Water has a density of 1 g/1 cc.
Compare the density of each water level of jar to the density of water to how well the jar floated.
Does density show when something will float or sink? Why do you think so?
A ship is made of iron, a very heavy metal but floats. Why does the ship float?

What I Found Out:
My jar had a diameter of 6.8 cm so the radius was 3.4 cm and a height of 12 cm. This gave it a volume of 435.6 cc.
When I filled it with water and massed it, the mass was 736.5 g. The empty jar was 251.7 g so the volume by that method was 484.8 g or cc.
Since my jar had a mass of 251.7 g, the empty jar had a density of 0.6 g/cc. The jar floated on top of the water.
I did not measure the water very carefully but the mass was the important thing.
After adding the first amount of water, the mass went up to 332.9 g and the density went to 0.8 g/cc. The jar still floated sideways and high.

The jar floats upright so the water in the bucket is a little over the water level inside the jar.

The second amount of water increased the mass to 406.1 g raising the density to 0.9 g/cc. The jar still floated but with the bottom angled down into the water.
The third amount of water increased the mass to 443.6 g raising the density to 1.0 g/cc. The jar now floated upright in the water with most of the jar under water.
The fourth amount of water increased the mass to 482.4 g raising the density to 1.1 g/cc. The jar still floated but was much lower in the water.
The fifth amount of water increased the mass to 546.6 g raising the density to 1.3 g/cc.. The jar floated but only the lid was still above water.
The sixth amount of water increased the mass to 595.4 g raising the density to 1.4 g/cc. Now only the very top of the lid was above the water.
The seventh amount of water had a mass of 631.7 g raising the density to 1.5 g/cc. The jar sank immediately to the bottom of the bucket.
If I used the volume from filling the jar with water, the densities were less. They were: empty 0.5 g/cc; 1st 0.7 g/cc; 2nd 0.8 g/cc; 3rd 0.9 g/cc; 4th 1.0 g/cc; 5th 1.1 g/cc; 6th 1.2 g/cc; and 7th 1.3 g/cc.
When the jar floated each time, the water level outside was a little higher than on the inside. This difference increased a little each time.

When the density is a little more than the density of water, the jar sinks.

The jar barely floated once the density of the jar was the same as the density of water. The density didn’t need to be much more than that of water before the jar sank.
For the jar density does seem to match to how well the jar floated. This might have been more striking if I had a more precise volume for my jar. I think density determines whether the jar sinks or floats because the jar floated with the air part above water and the full part below until the density got too much and it sank.
Ships work the same way. They have big rooms filled with air to make the ship’s density less than the density of water. This makes them work just like the jar.

# OS4 Water Surface

Do you know what a water strider is? Perhaps you’ve seen one or a group of them skating across the surface of a pond. Why don’t they sink?

Water striders prefer quiet areas of streams and ponds. They scavenge food like drowned insects floating on the water surface as the striders appear to skate their way along.

The reason water striders can walk on water is one of the special things about water. Every liquid has a place where the liquid stops and the air begins but the water surface is tough.

Question: What is special about the water surface?

Materials:

Measuring cup with 2 cups of water

Paper towels

Penny

Eye dropper

Bowl

Needle

Jar

Dish soap

Procedure:

Fold a paper towel in half and put it on the table

Put a penny in the center of the paper towel

Predict how many drops of water you think can be put onto a penny before they run off

Put 1 drop of water on the penny

A single drop of water on a penny doesn’t spread out. It holds together in a tight high half sphere because of water surface tension.

Observe and describe the shape of the drop

Use the eyedropper to put water, one drop at a time, on the penny

Remember to count how many drops of water you put on the penny

The water holds together under that water surface so tightly that even ten drops doesn’t cover the entire penny.

Stop every 10 drops to observe the shape of the water on the penny

Continue adding drops of water until the water runs off the penny onto the paper towel

Dry off the penny and set it aside

Pour water into the bowl until it is half full

Take the needle and carefully set it flat on the surface of the water in the bowl

A needle is a flat piece of metal but it still sits on top of the water surface.

Describe the surface of the water around the needle

Take the needle out of the bowl, dry it and set it aside

Pour the water back into the measuring cup

Pour water into the jar until it is a third to half full

Describe the water surface in the jar

The meniscus is the reverse of the water drops with the lowest part in the center and the highest parts going around the edge.

Pour the water back into the measuring cup

Add 5 drops of dish soap to the water in the measuring cup

Fold a dry paper towel in half and set it on the table

Set the penny in the center of the paper towel

Predict how many drops of water will sit on the penny before it runs off

Put 1 drop of soapy water on the penny

A little soap changes the shape of a drop of water a lot as this drop on a penny shows. The water surface is no longer that high tight form but a flattened puddle.

Observe and describe the shape of the drop

Use the eye dropper to put drops of water, one at a time, on the penny

Remember to count the number of drops

Stop every ten drops and observe the shape of the water surface on the penny

Continue adding drops until the water runs off onto the paper towel

Clean up the paper towel and penny

Pour soapy water in the bowl until it is half full

Carefully place the needle flat on the surface of the water

Describe what happens

Take the needle out of the bowl

Pour the water back into the measuring cup

Pour water into the jar until it is a third to half full

Describe the water surface in the jar

Clean up

Observations:

Prediction of drops of water on a penny:

Number of drops of water you put on the penny

Descriptions of the water surface on the penny

Twenty drops of water make a penny look like a dome with the rounded water surface.

Description of the water surface around the needle

Description of water surface in the jar:

Prediction of drops of soapy water on a penny:

Number of drops of soapy water you put on the penny:

Descriptions of the soapy water surface on the penny:

Description of what happens placing a needle on soapy water:

Description of the soapy water surface in the jar

Conclusions:

What do you think the water surface is doing as the drops pile up on the penny?

Does this explain why the needle can sit on the water in the bowl?

Does this explain why a water strider can walk on water?

Why can’t a cat or dog walk on water?

In the jar water still has a small meniscus but much less than the plain water had.

Compare the meniscus or dip on the surface of the water in the jar of plain water and soapy water.

What does the soap seem to do to the water’s ability to make this surface layer?

Ten drops of plain water didn’t touch the edges of the penny but ten drops of soapy water do.

Could a water strider walk on soapy water?

What I Found Out

After setting up the penny I put one drop of water on the center. The drop didn’t spread out. It stayed in a high found half sphere.

I thought I could put 25 drops of water on the penny before it ran off onto the paper towel. This was much less than the 36 that did sit on the penny.

Ten drops later the water didn’t even touch the edge of the penny. The water stayed in the high round half sphere.

Twenty drops later the water finally touched the edges of the penny. The water was still in that high round half sphere. The water seemed to hold itself together like it had a skin on it to hold the liquid inside.

Thirty drops of water bulge upward and outward on the penny.

The half sphere kept getting higher until 30 drops of water were piled on the penny. Drop 36 finally made the water run off the penny.

My needle floated on top of the water. The surface of the water seemed to make a dip around it. It was like the skin on the surface of the water molded itself around the needle.

This water skin on the surface would hold up a water strider or other small insect. A large insect or animal like a cat would be too heavy breaking the skin and sinking.

The water in the jar was lower in the center than around the edges. The edges seemed to almost climb up the jar.

Since so many drops of water sat on the penny, I thought at least 30 drops of soapy water would sit on the penny. This was far too many as only 22 drops did.

The first drop looked a lot different sitting on the penny. The drop was more spread out and not as high.

Ten drops of soapy water didn’t quite go to the edges of the penny but took up more room than the plain water had as it was wider and not as tall.

Twenty drops of soapy water barely stay on top of the penny.

Fifteen drops of soapy water went to the edges of the penny. The next six drops made the water taller but it was flatter than the plain water. Drop 22 made the soapy water run off onto the paper towel.

When I tried to put the needle on the surface of the soapy water, it sank immediately. I dried the needle and tried again but the needle would not float on the soapy water.

The dip in the water in the jar was less. Water didn’t seem to try to climb up the sides like the plain water did.

The soap seems to stop the skin from forming on the water surface. Without that skin to stand on, a water strider would sink just like the needle did.

About Water Molecules and Surface Tension

We know now that everything is made up of atoms and molecules. Water molecules have two hydrogen atoms attached to an oxygen atom.

These three atoms don’t line up flat. Instead they form an angle with the oxygen atom at the point.

This lets the water molecules line up ≪≪≪≪<. The oxygen atom likes the hydrogen atoms near it so they hang onto each other. This is especially true at the water surface.

The surface becomes very tough, for molecules and is called surface tension. It lets the water surface curve and climb up the side of a jar a little ways. It lets insects like water striders walk on it.

Soap breaks up this lining up of water molecules. They can’t hang onto each other any more. The surface tension gets weak so even a water strider will break through.

# OS3 Volume of Water

Volume is a measure of how much stuff is in so much space. This is a special kind of space.

A line goes between two points or places. You can’t put much stuff into a line.

When you have several lines joined together, you have a shape. You can put stuff into the space between the lines but only one layer deep.

If you have a lot of the same shapes piled up on top of each other, you can put lots of stuff inside the space inside. Volume has three parts: length, width and depth.

In chemistry the basic volume has a length of 1 cm, a width of 1 cm and a depth of 1 cm. The amount of space is 1cm x 1 cm x 1 cm or 1 cm3 or 1cc [cubic centimeter].

For gases this basic measure is increased to 1 cubic meter. We can see why by comparing how water volume and air volume behave.

Question: How do water volume and air volume compare?

Materials:

1 or 2 syringes holding 12 cc to 20 cc

Note: You can probably get these from a veterinarian. You do not need needles.

Tape

10 cm length of aquarium or other soft plastic tubing that fits tightly on the syringe

Paper

Custard cup of water

Procedure:

Note: If you have only one syringe, do everything with the air, then do everything with the water.

Pull the plunger back on one syringe to the highest mark to fill it with air

Record how much air is in the syringe

Put a piece of tape over the open end and fold it around the end to seal the syringe.

Hold a finger over the tape on the end and push down on the plunger until it stops

Record the reading of air in the syringe

Put the end of the other syringe in the water and pull back on the plunger a little ways

There will be air in the syringe so turn the end straight up and push down on the plunger until the air is out

Now fill the syringe to the same mark as the air

Water is drawn up into a syringe which is sealed up. Can you push on the plunger and make the water take up less volume?

Record the amount of water in the syringe

Dry the end of the syringe and tape it closed

Hold a finger over the taped end and push down on the plunger until you can’t push it down any more

Record the amount

Push the end of the tubing onto the end of the syringe

Tape the tubing tightly onto the syringe so it will not leak

Pull the plunger back filling the syringe with air to the same mark as before

Record the amount

Make a paper plug to push into the open end of the tubing

The paper plug seems to fill the end of the tubing. It is tight, as tight as I could make it. Will it stop the air from escaping?

Note: I make this paper plug by taking a small piece of paper about 20 cm square. I push down on the center and twist the outer part around tightly to make a cone. The end of the cone is pushed into the tubing then twisted in until I can’t get any more of the plug into the tubing.

Slowly push the plunger down observing how the volume changes and the plug acts

Pull the plug out of the tubing

Put the end of the tubing into the cup of water and half fill the syringe

Hold the end of the tubing straight up and pull all the water into the syringe

Push down on the plunger enough to push all the air out

Put the tubing back in the cup of water and fill the syringe to the same mark as before

Record the amount

Make a new paper plug and push it into the end of the tubing

Note: For this last part it is a good idea to go outside or inside a shower stall.

Slowly push down on the plunger observing how the volume changes and the plug acts

Observations:

Volume of air

Starting:

Ending:

How it feels pushing the plunger down:

Volume of water

Starting:

Ending:

How it feels pushing the plunger down:

Amount of air in tubing

Starting:

Ending:

How the volume and plug act:

Amount of water in tubing

Starting:

Ending:

How the volume and plug act:

Conclusions:

Did the amount of air in the syringe change or only the volume? Why do you think so?

Did the amount of water in the syringe change? Did the water volume change? Why do you think so?

Does air have a definite, unchanging volume? Why do you think so?

Does water have a definite, unchanging volume? Why do you think so?

How does this explain the changes in height you saw in the last Project?

Tractors and other big machines have fluid filled tubes to lift buckets and other parts. Pressure is put on the fluid at one end of the tube to move things on the other end. Why do they use fluid and not air? [This is called hydraulics.]

What I Found Out:

I had one 12 cc syringe so I did everything with air first. The first step was to pull air into the syringe and tape the end.

My syringe held 10 cc of air. When I held the tape on the end and pushed the plunger, it moved quickly to start with. Then it got harder and harder to push down until it stopped. The syringe now read 3 cc.

The amount of air in the syringe stayed the same but the volume didn’t because I could push the plunger down. Air has no definite volume and can be compressed or stretched out.

Next I taped the tubing on the syringe. I held the end firmly closed and pushed down on the plunger. this time it went down to 5 cc but crept back up to 6 cc when I quit pushing down.

I made a paper plug and pushed it into the end of the tubing. I thought this was very tight but, when I pushed down on the plunger, it went down all the way as the air leaked out around the paper plug.

After taking the tubing off the syringe, I filled it with 10 cc of water and taped the end. This time, when I pushed the plunger, the plunger would not move at all. The 10 cc of water stayed 10 cc so water has a definite volume.

Since the water takes up the same volume in any container, it will have a greater depth in a narrow space and a lower height in a wide space. This is what happened in the last Project.

Next I put the tubing back on the syringe. I put water in the syringe until it read 10 cc. Holding the end of the tubing, I pushed on the plunger and it did not move as I expected.

I made another paper plug and pushed it into the end of the tubing as tightly as I could. When I pushed on the plunger a few drops of water oozed out. Then the plug shot out of the tubing and across the lab table.

Machinery uses fluid because it doesn’t change volume. When pressure is put on one end, the pressure pushes on the other end to lift a bucket or other part.

I read in “Xplor” magazine from the Missouri Department of Conservation that bugs like spiders use hydraulics to move their legs. It gives them lots of power so jumping spiders can jump long distances very quickly to catch their next meal.

If you don’t get “Xplor” – it’s free to Missouri residents – check it out on the Conservation Department website http://www.mdc.mo.gov and sign up for it and “The Conservationist.”

# OS2 Changing Shape of Water

No matter what style of glass you pour water into, the water fits. You can pour water from a short fat glass into a tall skinny glass into a square glass. It still fits. Liquids like water are good at changing shape.

Changing shape is easy for water because it is a liquid. Water has no definite shape.

Does anything else change about water as it moves from one container to another?

Question: Does changing shape change anything else about water?

Materials:

Water

Tall skinny glass or jar

Short fat glass or jar

Square container

Scale

Ruler

Measuring cup

Procedure:

Mass the measuring cup

When measuring out water, remember it has a meniscus or dip in the surface. Water is measured to the bottom of the meniscus.

Pour 1 cup of water into the measuring cup and mass it

Mass the tall skinny glass

The problem with using this glass is how hard it is to see through it. I want to redo this project with a clear glass once I find one.

Pour the cup of water into the glass and mass it

Measure how wide the inside of the glass is in centimeters

Measure how high the water goes in the glass in centimeters

The volume of this jar will not be quite right as the bottom is not squared off. It is close.

Mass the short fat glass

Pour the water into it and mass it

Measure how wide the inside of the glass is

Measure how high the water goes in the glass

Mass the square container

When measuring any container for the inside volume, you are measuring the inside. This can be harder to do but the thick walls of this container distort the water volume results by almost 80 cc.

Pour the water into this container and mass it

Measure the sides of the container

Measure how deep the water is in the container

Pour the water into the measuring cup and mass it

Observations:

Amount of water to start:

Amount of water at the end:

Mass of water to start:

Mass of water at the end:

Analysis:

Subtract the mass of the empty container from the mass of the container of water to get the mass of water in the container.

The height of the water in the short fat jar is much lower than in the tall skinny glass.

Volume of a cylinder like a glass is the diameter times pi (3.14) times the height.

Volume of a square is the length of a side times the length of a side times the height.

The width is the diameter of the glass. Use the height of the water. Multiply to calculate the volume of water in each container.

Conclusions:

Did the height of the water change in the different containers?

Did the width of the water change in the different containers?

Compare how the height and width change.

Did the mass of the water change in the different containers?

Liquids like water change shape easily from round to square and back again.

Did the amount of water change as you poured it from one container to another?

How do you know?

What changes when water moves from one container to another?

What does not change when water moves from one container to another?

What I Found Out

I decided to measure out 250 ml of water. The water had a mass of 246 g.

When I poured the water into the tall glass, the height was 11 cm. The width was 5.4 cm so the water had a volume of 186.5 cc. The mass was still 246 g.

Glasses are slightly tapered. Jars have rounded bottoms. Square containers have rounded corners. Each affects the volume calculations a little.

When I poured the water into the fat jar, the height was only 8.1 cm. the width increased to 7.3 cm so the water had a volume of 185.7 cc.

When I poured the water into the square container, the water was 1.8 cm deep. The container was 10.6 cm by 9.5 cm so the water had a volume of 181.3 cc.

The height of the water was different in the different containers. The skinnier the container, the deeper the water was.

The mass of the water stayed almost the same. It got a little less from the beginning to the end.

The volume of the water did go down a little as I poured it into each container but stayed much the same. Each container was wet inside so some of the water did not our into the next one.

The amount of water stayed the almost the same because the mass and volume stayed almost the same. The changing shape was the only change in the water.

# OS1 Kinds of Water

Chemically all water has two hydrogen atoms attached to an oxygen atom. Since this is true, all water should be the same.

If this is true, why do companies bottle so many different kinds of water? Why do some people insist on using rain water to water some of their plants?

Question: Are there really different kinds of water?

Materials:

At least three water samples from different sources

Water sources: different brands of bottled water, rain water, tap water, creek water

Collecting water samples: (bottled water is in a container) Use a glass jar with a lid. Label the jar with where the water came from.

3 glasses for each kind of water (You can use the same 3 for all the samples washing them in between but it will make the Project take much longer.)

Procedure:

Write down where each water sample came from

Label 3 glasses or custard cups for each sample

I put the number on the jar label and on the cups. The quarter cup of water half filled these plastic cups.

Put 1/4 cup water in each cup (You will have 3 glasses of each sample kind.)

Put 1 glass of each kind of water in the refrigerator for 30 minutes

Take 1 glass out of the refrigerator

Note: Do NOT taste water from any source other than bottled water or tap water.

Write down what the cold water looks and smells like

If the water is bottled or tap water, taste the water by putting a small mouthful in your mouth and swishing it back and forth.

Write down what the water tastes like.

Get the glass of the same sample sitting on the counter

Write down what this sample looks, smells and tastes like

Put the third glass of this water sample in the microwave for 10 seconds

Write down what this sample looks, smells and tastes like

Repeat this with the glasses of other water samples

You can put 1/4 cup of each sample in a saucer or glass and set it out on the counter until the water evaporates.

Write down a description of any residue left behind in the container

Observations:

Write down where each water sample came from, the ingredients listed on the bottle, what the source looked like and where it is.

Each water sample has three cups. One cup spends half an hour in the refrigerator or maybe more. One sits on the table. The other goes in the microwave for 30 seconds. I tried fifteen and the water didn’t get hot.

Describe how each water sample looks, smells and tastes –

Cold:

Warm:

Hot:

Describe any residue left if you evaporated the water samples

Conclusions:

What color is water? Why do you think so?

What does water smell like? Why do you think so?

What does water taste like? why do you think so?

If you evaporated some water, was there anything in the water? What do you think this does to the water?

Does temperature change how different kinds of water smell and taste? Why do you think this happens?

Why can some people smell the rain? What are they really smelling?

What makes different kinds of water different?

Is all pure water the same?

What I Found Out

I didn’t smell any odor for any of my water samples. None of my samples had any color. All of my water samples felt wet.

Smell and taste differed in some of the water samples. The creek water had no smell when cold, a damp, musty smell when warm and a stronger musty smell when hot.

The rain barrel sample had no odor until it got hot. Then it smelled a little like when spinach is cooking.

Bottled water always tastes strange to me. It had a slightly dusty taste when cold that became a definite odd taste when the water was warm. Hot bottled water tastes like plastic.

The well water had a slight earthy taste when it was cold. The taste got stronger as the water got warmer.

The city tap water had a metallic taste. This too was slight when cold and got stronger as the water got warmer.

All of my water samples had no color so water must have no color. I did notice the rain barrel sample had a layer of green on the bottom. The green must be algae, tiny green plants.

None of my water samples had any odor so I think water has no odor. I have smelled odors in water before but the smells were from chemicals like chlorine or sulfur in the water, not the water itself.

The taste of water seems to be like the smell of water. The water itself has no taste. When the water does have a taste, it is from something in the water.

My water samples didn’t have time to evaporate yet. I will know more in a few days.

Temperature made a difference to tastes in the water. The colder the water, the less the taste.

I can smell the rain. It isn’t really the rain I smell, it’s things getting wet like hot, dry rocks or dirt.

Different kinds of water are different if they have different things in the water. The water itself is always the same with no color, odor or taste.

# Meet The Water Project

Hot days invite people to play in the water. We go swimming, boating, water sliding and playing in the sprinkler.

What is this water? What makes it so special? The Water Project will take a look at this liquid so necessary to life on Earth.

Why isn’t the surface of the water flat? The reason is one of water’s special properties.

What Is Water?

Chemically water is two atoms of hydrogen attached to an oxygen atom. The molecule is bent and has special electrical properties.

For life water is how we work. Our bodies are over 70% water. Watermelons are 90% water!

The special properties of water is why our bodies need that water for transporting all kinds of things, for doing chemical reactions and for staying cool.

The average person can survive close to a month without food. A week without water is deadly. In the desert that may shorten to a few hours!

The Water Project will explore some of the special chemical properties of water.

What Can Water Do?

We use water for lots of things. Transportation is one. Why does a boat float?

Water is used to operate machines. What properties of water make this possible?

Water is used to keep us and other things clean. Why can water do this so well?

Water can be very destructive. How can water move boulders?

In the upper reaches the Meramec River is still small but powerful enough to create and destroy gravel bars. What makes water so strong?

Water in Nature

Of course water is found in creeks, rivers, ponds, lakes and oceans. It supports fish and many other creatures from single celled creatures to giant whales.

This summer’s Water Project will not be visiting any of this. There is not enough time. Perhaps next summer we can explore this part of water.

What Will Become of The Water Project?

Like last summer’s pumpkin projects, these too will be included in a science book. Already I am planning the stories about wells, waste water treatment, dowsing and more.

How many puzzles can I create about water? I don’t know – yet. Which kinds of puzzles did you like the best in The Pumpkin Project?

There aren’t too many recipes for water. Those I know of are great summer treats. Perhaps I will find a few more specialties.

The water tower is a common site in many towns. Why are they built? How do they work?

Doing the Projects

Each week over June, July and the beginning of August there will be a project about some aspect of water. Some are simple and require very few materials. Others are more complex.

The first Project is up next week. Please join me for a summer of water fun.

# OS19 Counting Pumpkin Seeds

It’s easy to say the bigger the pumpkin the more seeds inside. But is this really true? And just how many seeds are in a pumpkin, anyway?

One way to find out is to count all of them. As you found out in the last Investigation, there are lots of them. Maybe it’s possible to estimate how many seeds there are.

In this Investigation, you can compare how many seeds are in two different pumpkins, a big one and a small one. You compare two different ways of counting the seeds.

When you are done counting the seeds, you can roast them to eat or save them to grow new pumpkins next year.

Question: How many seeds are in a pumpkin?

Materials:

2 ripe pumpkins (a small one and a big one)

Knife

1 Custard cup

3 Medium Empty Bowls

1 Big Empty bowl

Scale

Procedure:

Step 1: Open your Science Journal, write Investigation 19 and the date.

It’s important to mass the cup empty before putting the twenty seeds in.

Step 2: Label two bowls 1 and 2. Mass the custard cup and two bowls. Record these in the Table.

Be sure to write down the mass of the empty bowl so you can find the mass of the pumpkin seeds later.

Step 3: Cut one pumpkin open.

Step 4: Carefully pull handfuls of the strings and seeds out of the pumpkin dumping them in the unlabeled bowl. [You can use the seeds from Investigation 18.]

I like to use a soup spoon to scrape out all the pulp and seeds.

Step 5: Separate the seeds from the strings putting the seeds in Bowl 1. Some of the seeds may be very small and flat. Discard these with the strings.

Step 6: Mass Bowl 1 and the seeds. Record this in the Table.

Step 7: Count out 20 seeds. Put them in the custard cup and mass them. Record this in the Table.

Does the size of the seeds matter when you get the mass? If you include lots of little flat seeds, how will this change the mass?

Step 8: Count all the seeds moving them from one bowl into the unlabeled bowl. Be sure to add the 20 seeds put in the small bowl after massing them.

Step 9: Repeat with the second pumpkin using Bowl 2.

Observations:

How many seeds did you count for each pumpkin?

Pumpkin 1:

Pumpkin 2:

Counting each pumpkin seed individually takes a long time. Perhaps using seed mass will give an easier way.

Analysis:

Calculate the masses of the seeds [Subtract the mass of the bowl from the mass of the bowl and seeds mass]. Record this in Tables 1 and 2.

Estimate the number of seeds by first dividing the mass of 20 seeds by 20 to get the average mass of a seed. Then divide the mass of all the seeds by the average mass of one seed to get an estimate of how many seeds were in the pumpkin.

Do these two calculations for the second pumpkin.

Does the pulp or the seeds have more mass?

Conclusions:

Compare the total number of seeds from each of the two methods. Are they about the same?

How accurate is using mass to find the number of seeds? Why do you think this?

Which method is easiest to do? Why do you think this?

Do you think different sizes of pumpkins would have different numbers of seeds? Why do you think this?

Do you think different kinds of pumpkins have different numbers of seeds? Why do you think this?

Do you think using more than 20 seeds for a sample would make that method more accurate? Test this and find out.

Can you think of any other ways that might make these methods more accurate? Test these and find out.

# OS18 Inside a Pumpkin

Pumpkins look nice setting on a table but the parts to eat are inside that orange rind. Pumpkins have vitamins and minerals inside. It takes a chemistry lab to look for those. But other things are easy to look for so let’s look inside a pumpkin and see what we can find.

Note: Part of this Investigation asks you to cut a pumpkin into pieces. Pumpkins are difficult to cut. You may want an adult to cut the pumpkin up.

Note: If you use a clean table and kitchen knife, bowls and spoon, you can use the pumpkin to cook up some delicious pumpkin treats from the recipe section.

Question: What is a pumpkin made of?

Materials:

1 Ripe Pumpkin

Kitchen counter or newspapers on a table

Knife

Paring knife

Large spoon

Metric ruler

2 Bowls, labeled

Bathroom scale

Oven

Scale

Procedure:

Step 1: Open your Science Journal. Write “Investigation 18” and the date.

Step 2: Pick a ripe pumpkin. Describe and draw your pumpkin.

Step 3: Break off the stem piece. [It should snap off if pushed flat.] Draw and describe the end of the stem and where it joined the pumpkin.

Step 4: Weigh it on the bathroom scale to the nearest tenth of a pound. Record the weight in Table 1.

How is the seed pattern like the ovule pattern seen in Investigation 16? Why are some pumpkin seeds small and flat?

Step 5: Use the knife to split the pumpkin into top and bottom halves. This is difficult to do. Look at the seed patterns and compare it to the pattern of ovules you saw in Investigation 16.

Step 6: Measure the diameter in cm of the pumpkin. Record it in Table 2.

Step 7: Measure the diameter in cm from the inside edges of the flesh. Record it in Table 2.

Step 8: Measure how thick the rind is (You will have to estimate it.). Record it as the Middle thickness in Table 4.

Step 9: Measure how thick the flesh or wall is. Record it as the Middle thickness in Table 4.

Step 10: Mass Bowl 1. Record it in Table 3 in two places.

Step 11: Try to pull a seed out. Try to follow the string attached to the seed to the other end. Describe the string and seed.

Step 12: Pull the seeds and pulp out putting them in Bowl 1. Use the paring knife and spoon to remove as much of the strings as you can.

It takes a lot of scraping to get all the pulp and seeds out of a pumpkin.

Step 13: Mass the bowl, pulp and seeds. Record it in Table 3.

Step 14: Mass Bowl 2. Record it in Table 3.

Step 15: Separate the seeds from the stringy pulp putting them into Bowl 2.

Step 16: Mass Bowl 1 with pulp and Bowl 2 with seeds. Record these in Table 3.

Step 17: Weigh the empty pumpkin on the bathroom scale to a tenth of a pound. Record the weight in Table 1.

Step 18: Cut each half in half. The stem part will be difficult to cut through.

Will the circumference around the middle of this pumpkin be bigger than the circumference around the top and bottom? What’s in the middle of a pumpkin?

Step 19: Measure how thick the rind is at the stem end or top and at the blossom end or bottom of the pumpkin. Record these in Table 4.

Step 20: Measure how thick the flesh is at the top and bottom of the pumpkin. Record these in Table 4.

Step 21: Hold top and bottom pieces together and measure the diameter. Record it in Table 2.

Step 22: Measure the diameter between the inside edges of the flesh. Record this in Table 2.

Step 23: Write down the percentage of water you think is in a pumpkin.

Step 24: Cut out three square pieces of the flesh and rind about 1.5cm on a side. Mark 1, 2 and 3 on the rind end with a marker or pen.

Measuring several pieces of pumpkin instead of just one should be more accurate. Right?

Step 25: Mass each of the pieces. Record the masses in Table 5.

Step 26: Dry the pieces. You can use an oven set very low [200º or less], a dehydrator or a warm place. The time needed will depend on how you dry the pieces. The heat must be low so the pieces do not cook.

Step 27: When the pieces are very dry, mass them again. You may want to let the pieces dry a while longer just to make sure, then mass them again.

Note: Use the seeds for Investigation 19. Use the pulp for making pumpkin puree for the recipes.

Observations:

Is more of a pumpkin’s weight in the flesh or the pulp and seeds?

Describe the stem end of your pumpkin.

How does the circumference change for the inside and outside of a pumpkin?

Describe the arrangement of the seeds inside your pumpkin.

Describe the seeds.

Is there more pulp or seeds in a pumpkin?

Describe where the string goes from a seed to the pumpkin wall.

Describe how the seeds attach to the pulp.

Are the rind and pulp thicknesses the same all over the pumpkin?

Write down the percentage of water you think is in your pumpkin.

How much water is in a pumpkin? Does it matter how long since the pumpkin was picked?

Analysis:

After the pulp and seeds are out, the two halves of a pumpkin look like two thick orange bowls.

Table 1:

Subtract the weight of the empty pumpkin from the original pumpkin weight. Record it in Table 1.

Multiply the pounds by 2.2kg to find out how many kilograms each of the weights would be. Record it in Table 1.

Table 2:

Find the average outside diameter by adding the two outside diameters and dividing by 2. Write this in Table 2.

Find the average inside diameter by adding the two inside diameters and dividing by 2. Write this in Table 2.

Multiply the two diameters by p or 3.14 to find the circumference for the outside and inside of your pumpkin. Write these in Table 2.

Table 3:

Subtract the masses of the bowls to find the masses of the pulp and seeds together, pulp and seeds.

To do these calculations, be sure all the masses are in kilograms or in grams, not in both in the same calculation. Divide the mass of the empty pumpkin by the mass of the original pumpkin and multiply by 100%. Divide the mass of the pulp by the mass of the original pumpkin and multiply by 100%. Divide the mass of the seeds by the mass of the original pumpkin and multiply by 100%.

Table 5:

Subtract the dry mass from the original mass for each of the pieces. Write this in Table 5.

Find the averages by adding the three values in each column and dividing by three. Write this in Table 5.

Divide the difference by the original mass of the piece and multiply by 100% to find the percent. Write this in Table 5.

Dried pieces of pumpkin are much smaller than the original pieces. How much water is in a pumpkin?

Conclusions:

Is most of the weight of a pumpkin in the seeds and strings or in the pulp? Why do you think so?

If you wanted to breed a pumpkin for the most weight, is the size of the whole pumpkin or the thickness of the pulp more important? Why do you think this?

If one pumpkin is tall and thin and another is short and fat, how will this affect the width and height diameters?

When you average the width and height diameters, what shape of pumpkin are you ending up with? Why do you think so?

If you have a very heavy pumpkin and another the same size but much lighter, how will the outside and inside circumferences compare for the two pumpkins?

If you add up the separate masses of the seeds and pulp from Table 3, do you think it will be the same as the original mass? Try it. If the two masses are not the same, why is there a difference?

Why do you think the diameter of the rind stays the same but the diameter of the pulp changes in different parts of the pumpkin?

What does the rind do for the pumpkin?

Giant pumpkins are flat when they get very big. Why do you think this happens?

Why do you think each seed has a string attached?

What do you think would happen to a developing seed if its string broke?

Drying the pieces of pumpkin evaporated the water. How important is water to the weight of the pumpkin?

Why did you dry more than one piece of pumpkin? Were the percentages of water the same for all three?

Do you think a pumpkin picked a week before you dried pieces would have as much water in it as one you picked the morning before? Why do you think so?

If you were growing a pumpkin for a competition, how important is it to water your pumpkin plants regularly? Explain why you think this.

# OS16 Female Pumpkin Flowers

Investigation 15 looked at the male pumpkin flower. It only produces pollen, no pumpkins. The female pumpkin flower can grow into a pumpkin. Remember to pick your flower early in the morning and put the stem into a cup of water. Let’s look at a female flower.

Question: What parts are in a female flower?

Materials:

Female Pumpkin Flower

Metric ruler

Knife

Magnifying glass

Procedure:

Step 1: Open your Science Journal, write “Investigation 16” and the date.

Step 2: Examine the outside of the female flower. Measure how tall it is. Compare it to the diagram of a flower on page 101 and label your drawing with the parts you see.

Step 3: Smell the inside of the flower.

Step 4: Carefully cut or tear the petals off the flower.

Three green veins go up the outside of each of the five lobes of a pumpkin flower. Only the tops are orange.

Step 5: Examine the petals. Compare the inside and outside surfaces [look, color, feel etc.].

Step 6: Examine the inside of the female flower. Measure the pistil. Touch the pistil. You can safely taste the liquid on the pistil. Draw and describe what you observe.

Isolated from its flower a pumpkin flower pistil is a bumpy wet mound.

Step 7: Examine how the pistil joins the ovary [tiny pumpkin].

Step 8: Carefully slice the pistil and ovary in half lengthwise. Examine what you see in the two halves. Draw what you see.

Each line of ovules extends down the length of the pumpkin ovary. Each ovule has the potential to become a pumpkin seed.

Step 9: There should be a line of ovules or tiny seeds showing in the ovary. If there isn’t, cut a thin slice off the ovary to find a line of ovules.

Step 10: After you examine the line of ovules, cut across that half of the ovary and look for where lines of ovules are.

Observations:

Describe a female pumpkin flower

Label the parts on your drawing

Describe the outside of the petals

Inside a female pumpkin flower petal each main vein stands out in green against a pale yellow background. Only the tops of the petals are orange.

Describe the inside of the petals

Split in half its easy to see the single pistil isn’t single at all but several pistils clumped together.

Describe the pistil.

Describe the tiny pumpkin.

Describe how the inside of the pistil and ovary join

Describe the ovules

Number of ovules in one row:

Number of rows of ovules in half the ovary:

Number of ovules in half the ovary:

Number of ovules in the ovary:

Analysis:

Multiply the number of ovules in a row by the number of rows in half an ovary.

Multiply the number of ovules in half an ovary by two for the number of ovules in an ovary.

Conclusions:

If all the ovules in an ovary become seeds, how many seeds will there be in the pumpkin?

Each line of ovules is inside a spiral arm. Each half of an ovary has three lines of ovules.

If every ovule must join with one grain of pollen to become a seed, how many grains of pollen must be carried by insects to the pistil?

Why do you think the pistil is wet and sticky?

Magnified a pumpkin pistil has many bumps making its surface look grainy.

What do you think makes the pistil wet and sticky?

# OS15 Male Pumpkin Flowers

Pumpkins have two kinds of flowers. One flower makes pollen and is called a male flower. Most flowers on a pumpkin plant are male flowers. These have long thin stems called petioles. On the day you want to do this Investigation, go out early in the morning and pick a male flower. It may have insects in it. Use a long grass stem to push them out. Don’t knock the flower about, especially upside down or all the pollen will fall out! Put the flower into a glass of water until you are ready to look it over. It will wilt in just a few hours so let’s start early and find out about a male flower.

Question: What parts are in a male pumpkin flower?

Materials:

Male Pumpkin Flower

A male flower has a long, slim petiole. They rise up from leaf nodes, places where the leaf petioles join the pumpkin vine.

Metric ruler

Knife

Magnifying glass

Microscope

Slide and coverslip

Procedure:

Step 1: Open your Science Journal, write “Investigation 15” and the date.

Step 2: Examine the outside of the male flower. Measure how tall it is. Compare it to the diagram of a flower and label your drawing with the parts.

Looking inside a male flower it is easy to see the flower has five petals joined together. The stamens are joined into a single column. Around the base of the column is a trough evidently filled with nectar as insects congregate there. Larger insects would come in contact with the pollen on the stamen column getting it on their bodies so the pollen will be carried off when the insect leaves hopefully stopping by a female flower next.

Step 3: Smell the inside of the flower.

Step 4: Carefully tear or cut off the petals of the flower and lay them out on the table.

Step 5: Examine the petals. Compare the inside and outside surfaces – look, color, feel.

Step 6: Examine the stamen. Measure the stamen. Touch the stamen. Draw and describe what you observe.

Splitting a stamen lengthwise shows the inside is solid. The yellow concentric loops form a thin skin on the outside of the top half of the stamen.

Step 7: Put a drop of water on a slide. Put some of the pollen from the stamen on the water. Put on the coverslip.

Step 8: Examine the pollen with the microscope.

Step 9: Carefully slice the stamen in half lengthwise and examine the inside.

Magnifying the top of the stamen shows the concentric loops are yellow ridges on a pale base.

Observations:

Petals

The inside of the joined petals is smooth, slick, changing from yellow at the bottom to orange at the top. Large veins run down the center of each petal. The flower wilts quickly after being picked.

From the outside the joined petals are more greenish yellow at the base but still orange at their tops. Three veins are obvious on each petal lthough only the middle one is really big on the inside. The petals still feel smooth but don’t have a slick feel.

Conclusions:

Explain why you think a pumpkin flower has only one or has many petals joined (fused) together.

If a pumpkin flower has fused petals, how many petals are there? How can you tell?

What advantages would fused petals instead of separate ones give a pumpkin flower? (You might want to look at some flowers on your pumpkin plant in the early morning to get some ideas.)

Each seed in a pumpkin flower needs one grain of pollen to become a seed. Why are there so many more male flowers making pollen than female flowers (These have tiny pumpkins under them.)?

Why do you think the flower makes so much pollen since only one grain or piece is needed for each seed?

The large stamen has a big base with three feet. It sits in the center of a moat. The five sepals and petals are on the outside edge of this moat. The top of the stamen looks like an unexpanded mushroom but with concentric loops all over it. Pollen is found in the troughs of the loops.

Many flowers have lots of little stamens. A pumpkin flower seems to have only one. Does the pumpkin flower have fused stamens? Explain why you think so.

Different kinds of plants have pollen grains (separate pieces of pollen) with different shapes. Archeologists use fossil pollen to identify the kinds of plants that grew in an area long ago. What special things about a pumpkin pollen grain do you see?

# OS14 Pumpkin Leaves Have Layers

A pumpkin leaf is so thin, how can it have even thinner layers? How could we even see those very thin layers, if they are there? Those layers would be stuck together tightly and be hard to pull apart. Let’s take a look at a pumpkin leaf.

Note: I brought the wrong pictures. They were in the right folder but it must have been mislabeled. I will try to get the right ones here on Saturday.

Question: Do pumpkin leaves have layers?

Materials:

Big young leaf from a pumpkin plant

Microscope

4 Slides

Paper towel (Not all paper towels will do this. I used Viva Towels.)

Scissors

Penny

Rubbing alcohol

Pint glass jar

Procedure:

Step 1: Open your Science Journal, write “Investigation 14” and the date.

Part 1:

Step 2: Slowly tear off a piece of leaf between major veins. Try to do it at an angle to tear the top and bottom of the leaf apart.

A small triangle of leaf tore apart this time. This small bit of leaf layer will give lots to see under a microscope.

Note: This is difficult to do but you need only a small area, just a square mm or two. It may take tearing more than one leaf into small pieces to get a small area. Younger, thicker, moister leaves are easier to do. I pinch bits of the leaf between a thumbnail and finger then pull. It can take 20 or 30 tries and more than one leaf. Remember that the torn piece has a top on one leaf piece and a bottom on the other piece. Make two slides.

Step 3: Take areas where the leaf surfaces are torn apart and make slides with them. This requires only a very small piece of leaf on a drop of water

Step 4: Examine these slides with the microscope. Try to see the cells from the inside of the leaf.

Part 2: Chromatography

Step 5: Cut a piece of paper towel about 3cm wide and 3cm longer than your jar is tall.

Step 6: Draw a line across the piece of paper about 3cm from the end.

Rubbing a leaf with a penny crushes the cells and grinds the chlorophyll onto the paper towel.

Step 7: Put a piece of leaf over the line and rub it with the penny to leave a dark green spot on the paper.

Step 8: Attach the other end of the paper to the center of a pencil with some tape.

Step 9: Pour about 2cm alcohol in the jar

The mark on the paper is to make sure the spot is above the alcohol layer. Otherwise the chlorophyll will dissolve into the alcohol instead of go up the paper towel.

Step 10: Dangle the spotted end of filter paper in the alcohol making sure the spot does NOT touch the alcohol rolling up extra paper on the pencil.

Step 11: Watch the alcohol travel up the filter paper. When it is almost up to the pencil, take it out and examine what happened to the spot. The line will be faint and when the alcohol evaporates, everything will disappear. Draw what you see.

Observations:

Describe and draw the cells from the torn piece of leaf

The bottom layer of a leaf shows the clear epidermal cells and the stomates each surrounded by two green guard cells.

Describe what you see on the paper towel

Conclusions:

Does a leaf have layers? Why do you think so?

Where are most of the green cells containing chlorophyll found in a leaf?

Why do you think the cells on the top and bottom [called the epidermis] of the leaf are clear?

There are pairs of green cells called guard cells in the epidermis. Where are most of these cells found?

These cells surround openings called stomates into the leaf. Leaves need carbon dioxide from the air. Think back to Investigation 13. What does a stomate do?

Why do you think there are more stomates on the bottom of a leaf than on the top?

Compare the shapes of the epidermis cells and the cells inside the leaf.

The green coloring in the inside cells is chlorophyll. Why does this make it hard to see the cells?

The alcohol has spread the original spot but the marks are faint. They disappear once the towel dries.

Alcohol going up the paper towel holds onto the chlorophyll molecules and carries them up as it goes up. Each different kind of molecule is carried differently. Are all the chlorophyll molecules in a leaf the same? Are they all green? Why do you think so?

# OS13 Pumpkin Leaves

Not all plants have leaves (think about cactus) but most do. The leaves are many shapes and sizes. Pumpkin leaves are big and flat. So leaves must be important to a plant. Lots of insects and animals eat leaves so plants try to find ways to protect their leaves. You have seen that a plant collects water with its roots and sends that water to the leaves. Let’s find out ways pumpkin plants protect their leaves and use water.

Question: Why can leaves be thin but strong?

Materials:

Leaf with petiole from a pumpkin plant

2 Leaves on a pumpkin plant

Clear plastic bag, rubber band

Dark construction paper (brown or black), paperclip

Tincture of iodine

Magnifying glass

Knife

Procedure:

Step 1: Open your Science Journal, write “Investigation 13” and the date.

Part 1:

Step 2: Cut a 5cm x 12cm piece of dark construction paper.

Step 3: Fold the paper in half and place it around a pumpkin leaf on a pumpkin plant. Use the paperclip to hold it in place

Step 4: At least 24 hours later cut the leaf off the pumpkin plant and take it to where you do your Investigations.

Step 5: Take the paper off the leaf. Examine the leaf for any differences between where the paper was and where it was not. Do not leave the leaf in the light very long before the next step.

Step 6: Put drops of Tincture of Iodine on the leaf both where the paper was and on another similar piece of leaf.

Part 2:

Step 7: Put the clear plastic bag over a pumpkin leaf in the sun on a vine

Step 8: Use the rubber band or a paper clip to fasten the bottom of the bag around the petiole

Step 9: Wait 2 hours and take the bag off the leaf examining what is in the bag

Part 3:

Step 10: Cut a leaf and petiole off a pumpkin plant.

Step 11: Examine both sides of the leaf and petiole with the magnifying glass. Describe and draw what you see.

The leaf sits on top of the petiole with the main leaf veins going off to form each leaf lobe.

Step 12: Cut the petiole open flat where it joins the leaf and examine the area with the magnifying glass. Describe and draw what you see.

Step 13: Cut lengthwise down the petiole into the main leaf vein and examine how the petiole joins the vein with the magnifying glass. Describe and draw what you see.

Step 14: Tear across one piece of leaf. Does it tear in a straight line? Describe and draw what you see.

Pumpkin leaves are very thin and difficult to tear apart. A younger moister leaf is easier to tear so the top and bottom layers show separately.

Observations:

Part 1:

Describe the leaf where it was covered by the paper

Describe what happens when you put iodine on the leaf

Part 2:

Describe what you find in the plastic bag

Part 3:

Describe the leaf and petiole.

Describe how a petiole joins a leaf

Splitting open the veins where they leave the petiole and enter the leaf shows the five cords separate, each forming a main leaf vein.

Describe how the petiole veins and the leaf veins join

Describe tearing a leaf

Conclusions:

Why does the leaf change color when sunlight can’t get to it?

Iodine turns dark purple when it touches starch. Starch is made of many sugar molecules joined together. Where did you find starch in the pumpkin leaf? Why is it there?

What do you think the liquid in the plastic bag is?

Where do you think the liquid came from?

Why do you think the leaf loses the liquid?

What do you think would happen to a leaf if it couldn’t replace this liquid?

How is the petiole like a stem?

How is a petiole unlike a stem?

What happens to all the cords in the petiole when they get to the leaf?

Why does a pumpkin leaf need so many veins? Try to think of at least two things a leaf uses veins for.

A main vein is big with many short hairs and many spines on it. Side veins divide the leaf into tiny sections.

How do the veins affect how a leaf tears?

Why do you think pumpkin leaves have spines?

Why do you think some parts of a leaf are thin?

# OS12 Pumpkin Stem Parts

Not all plants have stems. Some plants like dandelions just have leaves. These plants can’t get very big. Stems come between the roots and the leaves letting a plant get big. Let’s see how a stem does this.

Question: How does a stem let a plant get big?

Materials:

1 pumpkin side vine about 1.5 m long

Knife

Magnifying glass

Jar of water with lots of food coloring (red or blue) in it

Procedure:

Step 1: Open your Science Journal, write “Investigation 12” and the date.

Step 2: Cut a side vine off a pumpkin vine

Step 3: Cut off a section of the stem with a leaf on the top end. Put the stem in the jar of water and set it aside overnight.

Step 4: Examine the rest of the side vine. What does it feel like? How long are the stem pieces (internodes) between leaf petioles? What shape is the stem?

Splitting open a pumpkin stem shows it is hollow. The inside is smooth but has cords running the length of the stem.

Step 5: Cut off a piece of stem from between two petioles to examine. Is it solid? Is it the same diameter at both ends? Is it the same all the way around? Try to tear it across. Try to tear it lengthwise. Does the inside feel the same as the outside? What else do you see?

Step 6: Examine the strings and soft parts with the magnifying glass. How many strings are there? Are they all the same? Try to cut some strings lengthwise to examine. [Be very careful not to cut yourself.]

Step 7: Cut open a section of vine so you can see how a leaf petiole joins the stem. Examine how the strings go from the stem into the leaf.

Pumpkin stems are hollow as are the petioles as shows in this cut open view. The white part is solid and will put out an adventitious root.

Step 8: Carefully cut off a tendril and examine it. What does it feel like? Is it hollow? Try to cut it lengthwise and see what is inside it. [Do this carefully.]

Step 9: Carefully cut off a white area from the stem below a leaf (the adventitious root) and examine it. How is it different from the stem?

Step 10: Examine the 5cm at the tip of the vine. Is it like the rest of the vine? What is found at the tip? Carefully cut the parts of the tip open to see what is inside.

Hidden within the tip of a pumpkin vine tip are all the leaves, flowers and tendrils that will be part of the vine.

Step 11: Examine flower buds on the vine by a leaf. Are the stalks like the vine? Do the cords go into the flower stems? Carefully cut open the flower buds. What is inside the buds?

Step 12: Take the piece of vine out of the food coloring. Cut across the end of the stem above where it was in the water. Can you find food coloring inside the vine?

Observations:

Use this section to write down and draw what you see.

Stem:

A stem cut across shows the five cords as round areas in the stem.

Petiole, Tendril and Stem:

Root and Stem:

Stem cross section plain (top) and food coloring:

Vine Tip:

Even when small a pumpkin leaf has the shape of a big leaf.

Leaves from the very tip to 5cm back:

Tendrils from the very tip and 5cm back:

A pumpkin tendril begins as a tiny spring then opens into a long whip that coils around whatever it touches.

Male Flower from tip whole (top) then cross section:

Female Flower from tip whole (top) then cross section:

Both the small male and female pumpkin flower buds are covered with long silky hairs.

Conclusions:

Compare tearing the stem across and lengthwise. Which way was easier? Why is this way easier?

What do you think the cords in the vine stems do?

How does the cord pattern change around the petiole? Why do you think the pattern does this?

How do the cords affect how the stem crushes?

What are the advantages of a hollow stem to the plant?

What are the disadvantages of a hollow stem to the plant?

Splitting open a male flower bud shows it is smaller than a female flower bud with only the petals and fused stamens waiting to open into a flower.

Where are the spines found on the stem? What do the spines do for the plant?

Why are the parts so small at the tip of the vine?

How do you think they get bigger? How can you test your idea?

Compare the growing tips of the sprout [from Investigation 10] and the vine. Why do you think a plant only grows longer at the tips?

How does a pumpkin plant use tendrils? Why is this important to the plant? [You can go out and look at the tendrils on your pumpkin plant.]

Carefully splitting a female flower bud in half shows he ovules waiting to become seeds and the pistil and petals waiting to open out into a flower.

Look back at Investigation 10. How has the stem changed from that of a sprout?

# OS11 Looking at Plant Roots

The next four Investigations look at the parts of a growing pumpkin plant so I have left all four in a row here but am only adding pictures for 11 today and will do 12 next week.

Although you can do each one separately, all of them can be done using the same side branch listed in the Materials part of Investigation 12. Most side branches have at least one adventitious root for Investigation 11. The stem is used for Investigation 12. The leaves can be used for Investigations 13 and 14. The vine will wilt overnight so all the Investigations would have to be done one after the other which will take several hours.

In Investigation 9 you examined a pumpkin sprout root. This time you will examine a root from a pumpkin plant to find out if it is the same or if it has changed as the plant grew big. Of course, once you dig a plant up by the roots, the plant will die. So you can examine the roots of a plant you are thinning out because a hill can only have so many plants growing in it or you can use an adventitious root, one that has grown from a pumpkin plant vine node. The best is to do both kinds to find out if they are the same. Let’s look at some roots.

Question: What are the parts of a root?

Materials:

A root from a pumpkin plant with the dirt carefully rinsed off

Knife

Magnifying glass

Microscope, slide

Procedure:

Step 1: Dig up a pumpkin plant root. If you pull it up, you will damage the roots.

Step 2: Rinse the dirt off the roots. Shake the roots gently in a pail of water but don’t scrub them or you will damage the roots. Not all of the dirt will rinse off.

Step 3: Spread the roots on a damp paper towel. Examine them by looking and with the magnifying glass.

Pumpkin adventitious roots usually grow from a stem node below a leaf with a flower bud. Why would this be a good place for an extra root?

Step 4: Cut off a piece of root and examine the cross section of the root

Step 5: Cut a section of root 3cm to 4cm long and try to cut it lengthwise. Examine the pieces.

Step 6: Cut off a tiny root off the main root, about 1cm long, place one or two on a drop of water on a slide and examine the pieces with a microscope.

Observations:

Draw the root.

Draw the very tips of the roots on the slide.

Move up the roots on the slide until you can see little hair-like roots sticking out. Draw these.

Conclusions:

A taproot has a main root with side roots branching off. A fibrous root has many roots that look alike coming from the end of the stem. Which kind of root does a pumpkin have?

The adventitious root quickly puts out lots of small rootlets to gather nutrients and water. this will give extra supplies of these for a pumpkin to grow from this node.

The very end of a root has a root cap, a bunch of cells on the end that rub off as the root grows. Why would a root need a root cap?

All but the very ends of the root have a thick layer of protective cells on them and can not absorb this water. Why do roots need this protective layer?

A plant uses a lot of water. The tips of the roots must supply all of the water. How would having lots of root hairs, the little stick out parts, help the root tips absorb more water?

Investigation 12

What Are the Parts of a Stem?

Not all plants have stems. Some plants like dandelions just have leaves. These plants can’t get very big. Stems come between the roots and the leaves letting a plant get big. Let’s see how a stem does this.

Question: How does a stem let a plant get big?

Materials:

1 pumpkin side vine about 1.5 m long

Knife

Magnifying glass

Jar of water with lots of food coloring (red or blue) in it

Procedure:

Step 1: Open your Science Journal, write “Investigation 12” and the date.

Step 2: Cut a side vine off a pumpkin vine

Step 2: Cut off a section of the stem with a leaf on the top end. Put the stem in the jar of water and set it aside overnight.

Step 3: Examine the rest of the side vine. What does it feel like? How long are the stem pieces (internodes) between leaf petioles? What shape is the stem?

Step 4: Cut off a piece of stem from between two petioles to examine. Is it solid? Is it the same diameter at both ends? Is it the same all the way around? Try to tear it across. Try to tear it lengthwise. Does the inside feel the same as the outside? What else do you see?

Step 5: Examine the strings and soft parts with the magnifying glass. How many strings are there? Are they all the same? Try to cut some strings lengthwise to examine. [Be very careful not to cut yourself.]

Step 6: Cut open a section of vine so you can see how a leaf petiole joins the stem. Examine how the strings go from the stem into the leaf.

Step 7: Carefully cut off a tendril and examine it. What does it feel like? Is it hollow? Try to cut it lengthwise and see what is inside it. [Do this carefully.]

Step 8: Carefully cut off a white area from the stem below a leaf (the adventitious root) and examine it. How is it different from the stem?

Step 9: Examine the 5cm at the tip of the vine. Is it like the rest of the vine? What is found at the tip? Carefully cut the parts of the tip open to see what is inside.

Step 10: Examine flower buds on the vine by a leaf. Are the stalks like the vine? Do the cords go into the flower stems? Carefully cut open the flower buds. What is inside the buds?

Step 11: Take the piece of vine out of the food coloring. Cut across the end of the stem above where it was in the water. Can you find food coloring inside the vine?

Observations:

Use this section to write down and draw what you see.

Stem:

Petiole, Tendril and Stem:

Root and Stem:

Stem cross section plain (top) and food coloring:

Vine Tip:

Leaves from the very tip to 5cm back:

Tendrils from the very tip and 5cm back:

Male Flower from tip whole (top) then cross section:

Female Flower from tip whole (top) then cross section:

Conclusions:

Compare tearing the stem across and lengthwise. Which way was easier? Why is this way easier?

What do you think the cords in the vine stems do?

How does the cord pattern change around the petiole? Why do you think the pattern does this?

How do the cords affect how the stem crushes?

What are the advantages of a hollow stem to the plant?

What are the disadvantages of a hollow stem to the plant?

Where are the spines found on the stem? What do the spines do for the plant?

Why are the parts so small at the tip of the vine?

How do you think they get bigger? How can you test your idea?

Compare the growing tips of the sprout [from Investigation 10] and the vine. Why do you think a plant only grows longer at the tips?

How does a pumpkin plant use tendrils? Why is this important to the plant? [You can go out and look at the tendrils on your pumpkin plant.]

Look back at Investigation 10. How has the stem changed from that of a sprout?

Investigation 13

What’s In a Leaf?

Not all plants have leaves (think about cactus) but most do. The leaves are many shapes and sizes. Pumpkin leaves are big and flat. So leaves must be important to a plant. Lots of insects and animals eat leaves so plants try to find ways to protect their leaves. You have seen that a plant collects water with its roots and sends that water to the leaves. Let’s find out ways pumpkin plants protect their leaves and use water.

Question: Why can leaves be thin but strong?

Materials:

Leaf with petiole from a pumpkin plant

2 Leaves on a pumpkin plant

Clear plastic bag, rubber band

Dark construction paper (brown or black), paperclip

Tincture of iodine

Magnifying glass

Knife

Procedure:

Step 1: Open your Science Journal, write “Investigation 13” and the date.

Part 1:

Step 2: Cut a 5cm x 12cm piece of dark construction paper.

Step 3: Fold the paper in half and place it around a pumpkin leaf on a pumpkin plant. Use the paperclip to hold it in place

Step 4: At least 24 hours later cut the leaf off the pumpkin plant and take it to where you do your Investigations.

Step 5: Take the paper off the leaf. Examine the leaf for any differences between where the paper was and where it was not. Do not leave the leaf in the light very long before the next step.

Step 6: Put drops of Tincture of Iodine on the leaf both where the paper was and on another similar piece of leaf.

Part 2:

Step 7: Put the clear plastic bag over a pumpkin leaf in the sun on a vine

Step 8: Use the rubber band or a paper clip to fasten the bottom of the bag around the petiole

Step 9: Wait 2 hours and take the bag off the leaf examining what is in the bag

Part 3:

Step 10: Cut a leaf and petiole off a pumpkin plant.

Step 11: Examine both sides of the leaf and petiole with the magnifying glass. Describe and draw what you see.

Step 12: Cut the petiole open flat where it joins the leaf and examine the area with the magnifying glass. Describe and draw what you see.

Step 13: Cut lengthwise down the petiole into the main leaf vein and examine how the petiole joins the vein with the magnifying glass. Describe and draw what you see.

Step 14: Tear across one piece of leaf. Does it tear in a straight line? Describe and draw what you see.

Observations:

Part 1:

Describe the leaf where it was covered by the paper

Describe what happens when you put iodine on the leaf

Part 2:

Describe what you find in the plastic bag

Part 3:

Describe the leaf and petiole.

Describe how a petiole joins a leaf

Describe how the petiole veins and the leaf veins join

Describe tearing a leaf

Conclusions:

Why does the leaf change color when sunlight can’t get to it?

Iodine turns dark purple when it touches starch. Starch is made of many sugar molecules joined together. Where did you find starch in the pumpkin leaf? Why is it there?

What do you think the liquid in the plastic bag is?

Where do you think the liquid came from?

Why do you think the leaf loses the liquid?

What do you think would happen to a leaf if it couldn’t replace this liquid?

How is the petiole like a stem?

How is a petiole unlike a stem?

What happens to all the cords in the petiole when they get to the leaf?

Why does a pumpkin leaf need so many veins? Try to think of at least two things a leaf uses veins for.

How do the veins affect how a leaf tears?

Why do you think pumpkin leaves have spines?

Why do you think some parts of a leaf are thin?

Investigation 14

Leaves Have Layers

A pumpkin leaf is so thin, how can it have even thinner layers? How could we even see those very thin layers, if they are there? Those layers would be stuck together tightly and be hard to pull apart. Let’s take a look at a pumpkin leaf.

Question: Do pumpkin leaves have layers?

Materials:

Big young leaf from a pumpkin plant

Clear tape

Microscope

4 Slides

Paper towel (Not all paper towels will do this. I used Viva Towels.)

Scissors

Penny

Rubbing alcohol

Pint glass jar

Procedure:

Step 1: Open your Science Journal, write “Investigation 14” and the date.

Part 1:

Step 2: Put a small piece of tape [about 1.5cm long] on the top of the pumpkin leaf between the major veins. Press all but one corner down firmly on the leaf.

Step 3: Starting with the loose corner, pull off the piece of tape, attach it to the center of a slide and label the slide.

Step 4: Put another piece of tape on the same spot, press all but one corner down firmly, remove it and put it on a slide. Label the slide.

Step 4: Turn the leaf over and do two more pieces of tape putting them on slides. Label the slides.

Step 5: Examine the slides with the microscope. The first pieces of tape on top and bottom may just have leaf hairs and debris on them. The second pieces should have cells from the top and bottom layers of the leaf. Draw what you see.

Part 2:

Step 6: Slowly tear off a piece of leaf between major veins. Try to do it at an angle to tear the top and bottom of the leaf apart. This is difficult to do but you need only a small area, just a square mm or two. It may take tearing more than one leaf into small pieces to get a small area. Younger, thicker leaves are easier to do.

Step 7: Take areas where the leaf surfaces are torn apart and make slides with them. This requires only a very small piece of leaf on a drop of water

Step 8: Examine these slides with the microscope. Try to see the cells from the inside of the leaf.

Part 3: Chromatography

Step 9: Cut a piece of paper towel about 3cm wide and 3cm longer than your jar is tall.

Step 10: Draw a line across the piece of paper about 3cm from the end.

Step 11: Put a piece of leaf over the line and rub it with the penny to leave a dark green spot on the paper.

Step 12: Attach the other end of the paper to the center of a pencil with some tape.

Step 13: Pour about 2cm alcohol in the jar

Step 14: Dangle the spotted end of filter paper in the alcohol making sure the spot does NOT touch the alcohol rolling up extra paper on the pencil.

Step 15: Watch the alcohol travel up the filter paper. When it is almost up to the pencil, take it out and examine what happened to the spot. The line will be faint and when the alcohol evaporates, everything will disappear. Draw what you see.

Observations:

Describe and draw the cells from each piece of tape

Describe and draw the cells from the torn piece of leaf

Describe what you see on the paper towel

Conclusions:

Does a leaf have layers? Why do you think so?

Where are most of the green cells containing chlorophyll found in a leaf?

Why do you think the cells on the top and bottom [called the epidermis] of the leaf are clear?

There are pairs of green cells called guard cells in the epidermis. Where are most of these cells found?

These cells surround openings called stomates into the leaf. Leaves need carbon dioxide from the air. Think back to Investigation 13. What does a stomate do?

Why do you think there are more stomates on the bottom of a leaf than on the top?

Compare the shapes of the epidermis cells and the cells inside the leaf.

The green coloring in the inside cells is chlorophyll. Why does this make it hard to see the cells?

Alcohol going up the paper towel holds onto the chlorophyll molecules and carries them up as it goes up. Each different kind of molecule is carried differently. Are all the chlorophyll molecules in a leaf the same? Are they all green? Why do you think so?

# OS10 Looking at Pumpkin Sprout Stems

Roots absorb water from the soil and send it to the leaves. To get from the roots to the stems the water must travel through the stems. When the leaves make sugar, they send it to the roots through the stems. Let’s find out how water travels through a stem.

Question: What does a pumpkin sprout stem do?

Sprout stems are mostly a greenish white color. The food coloring makes it easier to see some of the parts of the sprout.

Materials:

2 Sprouted Pumpkin Seeds or the sprouts from Investigation 9

Knife

Magnifying glass

Custard cup

Pint Jar

Water

Food coloring (red or blue)

Procedure:

Step 1: Open your Science Journal, write “Investigation 10” and the date.

Step 2: If you are using new sprouts, not the ones from Investigation 9, you need to put one in a jar of water with food coloring in it just as you did for that Investigation.

A sprout has roots leading into a stem with cotyledons and a true leaf on it.

Step 3: Take the sprout out of the plain water and cut the stem off about 3cm above the roots. Set the top half with the leaves back in the cup of water. Cut the roots off about 1cm down and set the roots back in the cup of water. Carefully split the stem in half lengthwise. Try to cut it down into the root.

Sprout roots are white. Stems are green.

The seed coat is attached where the sprout root and stem meet.

Step 4: Examine the split pieces with the magnifying glass.

Splitting open a sprout stem shows the root part is solid but the stem is hollow.

Step 5: Take the sprout out of the water with food coloring. Cut it off about 3cm above the roots. Set the top half with the leaves back in the water with food coloring. Cut the roots off about 1cm down and set the roots back in the water with the food coloring.  Carefully split the stem in half lengthwise. Try to cut it down into the root.

The sprout roots appear blue but the stem doesn’t except where some food coloring got smeared.

Step 6: Examine the split pieces with the magnifying glass.

The blue food coloring moves up through the thin walls of a sprout stem.

Step 7: Take the top piece out of the plain water. Carefully cut a very thin piece, as thin as a piece of paper, off the end of the stem.  Place a drop of water on a slide and put the piece on it. Do the same with the top from the water with food coloring in it. Place both tops back in their cups of water.

The food coloring is in special places in the sprout stem. This shows that water moves through a stem in special places, not all over.

Step 8: Examine them through the microscope.

Step 11: Clean the slide and cover slip.

Step 12: Examine the top from the water with the food coloring with the magnifying glass. Try to see where the food coloring goes when it reaches the leaf. What parts can you identify in the growing tip?

Step 13: Discard the pieces of sprouts and clean up.

Observations:

Plain stem:

Describe the outside of the stem

Describe where the stem and root meet

Describe the inside of the stem

Describe where the stem and root meet

Describe and draw what you see in the thin slice

Food colored stem:

Describe the outside of the stem

Describe where the stem and root meet

Describe the inside of the stem

Describe where the stem and root meet

Describe and draw what you see in the thin slice

Iodine turns purple in the presence of starch which is made of sugar. Describe where the iodine turns purple.

Describe where the food coloring goes in as it enters the leaves

Conclusions:

Compare the stem and root parts of the sprouts. Can you tell where one ends and the other begins?

Why would the stems and roots be similar?

Where do you think the water and sugars move through a stem?

Why is it better to have the water and sugars move in special places?

What do you think the other parts of the stem do?

What do you think a stem does? [Think about a tree. Its trunk is a stem.]

# OS9 Looking at Sprout Roots

Up to now I think the Investigations are pretty complete including the pictures. Starting with this Investigation there are some pictures missing because I split much larger Investigations into two different ones and made some other changes.

When you complete an Investigation, please let me know if something isn’t clear or doesn’t seem to work with the procedure I have given. This will help me fix those problems.

One thing you learn as a writer is how easy it is to see what you think you wrote instead of what you actually wrote. This is why a writer sends a book to an editor. For these Investigations, you are my editors.

Outside Project 9

Looking at Sprout Roots

No matter which way a seed points, the root still grows down into the soil as you saw in Investigation 4. A plant needs lots of water to grow and make sugar. The air is too dry so this water must come from the soil. Since the root is in the soil, it must get the water and send it to the rest of the plant. First let’s find out about how water moves through a sprout root. Then go on to Investigation 10 to see how water moves through a stem.

Question: How does water move through the roots of a sprout?

Materials:

2 Pumpkin sprouts with their first true leaves

Jar

Water

Food coloring (red or blue)

Knife

Paper towel

Magnifying glass

Procedure:

Preparation: You will need 2 pumpkin sprouts for this Investigation. You can use the same ones for the next Investigation if you do them the same day. You can start the seeds in a cup of dirt or you can start them in a glass jar like you did for Investigation 4. Using the glass jar lets you see how the roots grow and you don’t have to clean the dirt off.

Step 1: Open your Science Journal and write “Investigation 9” and the date.

Step 2: Put water in the jar so it is half full and add food coloring to make it dark.

When a sprout root absorbs water full of food coloring, the color goes with the water and shows where the water goes inside the root.

Step 3: Take the two sprouts out of the cup. Wash the dirt off the roots.

Step 4: Prop one sprout in the cup so the roots are in the colored water and the cotyledons and leaves are out of the water. Set it aside until color appears in a leaf. This can take up to a day.

Step 5: Set the other sprout on a moist paper towel. Examine it with the magnifying glass.

Step 6: Carefully spread the roots out and examine the roots carefully from the tip to the cotyledons. Draw and describe the roots.

A pumpkin sprout has a main root that quickly branches off into many smaller roots.

Step 7: Cut about 1cm of the main root tip off with your fingernails or the knife. Put the rest of the sprout in a cup of water so the roots are in and the top is out of the water.

Step 8: Place the root tip on the table.

Step 9: Examine the root tip using the magnifying glass.

Step 10: Carefully split the root tip piece lengthwise and examine the cut sides with the magnifying glass.

Step 11: Take the second sprout out of the jar, rinse it, place it on a moist paper towel, carefully spread the roots and examine them with the magnifying glass.

Food coloring makes a sprout’s roots easier to see.

Step 12: Cut about 1cm off the main root tip. Put the rest of the sprout back in the jar with the food coloring.

Step 13: Place the cut root tip on the table.

Step 14: Examine this piece using the magnifying glass.

Step 15: Carefully split this piece lengthwise and examine the cut sides with the magnifying glass.

Observations:

Describe the roots on the sprout without coloring:

A sprout root piece shows the root has a main piece with small rootlets going off of it.

Describe the roots on the sprout from the colored water:

Food coloring starts in the small rootlets and moves into the bigger root.

Describe the tip of the roots, plain and colored:

Describe the tops of the roots where they join the stem, plain and colored:

Splitting the sprout root open where it joins the stem shows the root is solid and the stem is hollow.

Conclusions:

Was it easier to see the different parts of the root with or without the coloring in the sprout? Explain.

What does the tip of the root do in the soil as the root grows? Why would cells here have to be different than in other parts of the radicle?

Why does the very tip of the root not absorb water?

Where are the cells that take water up the root to the plant located? Why are they located here?

Blue food coloring goes up through the outside parts of a sprout root so water must go up this way too.

How does the outside of the root change above where water is absorbed?

Why would this make it hard for this part of the root to absorb water?

# OS8 Important Sprout Parts

When a seed starts to grow it has the four parts you looked at earlier. The plant embryo puts down a root. It puts up a stem. A pumpkin sprout has seed leaves or cotyledons full of stored food. Then it makes pumpkin leaves. Sometimes a bug eats one of these parts. Let’s find out which parts a sprout must have to grow into a plant.

Question: Can a sprout become a plant if part of it is missing?

Materials:

4-Styrofoam cups

8-Pumpkin seeds

Potting soil

Water

Tray

Procedure:

Step 1: Open your Science Journal, write “Investigation 6” and the date. Copy Table 1 into your journal. You will start your observations after doing Step 6.

Step 2: Label the Cups 1 to 4. Put potting soil in the cups and firm it. The top should be 1.5cm from the top of the cup. Add water so the soil is damp but not soggy.

All the pumpkin seeds are planted in the same kind of soil at the same depth.

Step 3: Push two pumpkin seeds into each cup until they are 2cm deep. The seed should be pushed in sideways.

Step 4: Cover the seeds with soil. Put the tray in a safe warm place. Water them if they get dry but don’t make them soggy. You can put plastic wrap over the tops to keep them from drying out.

Step 5: Check the cups everyday until the seeds germinate.

Step 6: Be very careful doing this part. You will use your thumbnail to pinch some part off six of the seedlings. The parts are very small and close together so it is easy to pinch off a part you don’t mean to. This is why you wait until after doing this part to number the Cups.

One Cup: Remove only the cotyledons and leave the growing tip.

Second Cup: Remove the growing tip but leave the cotyledons alone.

Third Cup: Remove both the growing tip and the cotyledons.

Fourth Cup: Leave these sprouts alone.

When all eight sprouts are up, two are left alone, two have the cotyledons removed, two have the growing tip removed and two have both the cotyledons and growing tip removed.

Step 7: Set the cups in a bright place but not in the sun. Water them if they get dry but don’t make them soggy.

Step 8: Check the sprouts every day to see how they grow until the sprouts you did not pinch anything off of have their first true leaves. Describe what the sprouts are doing in Table 1.

Observations:

Describe the sprouts before you remove any parts

Predict what will happen to each of the sprouts after you remove part of them.

Conclusions:

Describe how a pumpkin sprout comes out of the soil.

How does this protect the new seedling?

A pumpkin sprout must have cotyledons to grow. if these or these and the growing tip are missing, the sprout will die.

How well did your predictions match what happened?

Which parts are necessary for a pumpkin sprout to grow into a plant? Explain.

# OS7 Light and Sprouts

My seeds have sprouted. My sprouts are getting bigger. Perhaps yours are too. Here is Part 3 about growing the pumpkin vines with ideas about things you can study about them.

It’s time to start showing off our pumpkin plants. I will start a page of photo galleries of pumpkin plants. To get your own gallery so you can show everyone how well your pumpkins are doing, email me pictures of your pumpkin plant as it grows.

Project 1

Part 3

This is the hardest part of growing pumpkins for me. Maybe it is for you too. It only takes a few days to a week for the sprouts to appear but the time seems so long. One day there is that hook pushing soil aside or cotyledons open and pumpkin plants are growing.

The next step is keeping those plants growing and healthy.

Getting Started

Step 1: Only two miniature or sugar pie pumpkin plants can grow in one hill. Only one larger pumpkin plant can grow in a hill. More than two seeds should germinate so some have to go. Sometimes you can tell a sprout is very small or doesn’t grow very well. Pull these sprouts out. When they get their first true leaves, pull the smallest one. Do this again when the fourth true leaves appear until only three miniature or pie plants are left or two bigger pumpkin plants. Let the one grow to half a meter long, dig it out carefully and use it for Investigation 11. If the sun is very hot on your pumpkin plants almost all day, put up a shade to protect the plants from sunburn and dying. You can tell the sun is too hot if the edges of the cotyledons or leaves get dry and brown or they fade to light green.

Note: I hate to pull out a nice sturdy sprout and toss it away. It’s trying so hard to grow well. But it can’t stay where it is or none of the plants will do well later on. One solution is to transplant it someplace else. Pumpkins grow well with corn.

Step 2: While the plants are small, water them directly during the day. Once the plants start vining, water the vines by filling the moat and letting it soak in. While the vines are small, they may not need water every day unless it is hot. If the leaves wilt in the afternoon, you are not watering enough. Try not to get water on the leaves. Water your plants after the dew is gone but by early in the afternoon so the leaves get dry before sunset.

Getting Bigger

Step 3: Pumpkin vines grow extra or adventitious roots at every leaf node. The vines also grow in any direction. Before the roots grow, carefully move the vines to grow across your garden space. It’s best to do this while the vines are small and move them in the afternoon when the vines are softer. If the vine needs to be moved very far, do a little each day so you don’t break or bend the vine.

Step 4: The extra roots give you another way to feed the vines extra nutrients. This is very important for Halloween and giant pumpkins. For these vines, dig a little hole under the leaf node, put extra manure in it and cover it with dirt. Put dirt over the vines (not the leaves) to help protect them from borers and squash bugs. The dirt helps the adventitious roots grow faster.

Step 5: Especially for giant pumpkins, you may need to trim the vines and side vines when they get really long.

Step 6: Check your vines every day for insect pests and diseases. Pick off squash bugs and their eggs. Spray for cucumber beetles and flea beetles.

Keeping Records

Measure your plants for several days to find out how fast they grow. Write down how the plants change as they grow. Look at your plants at different times of the day and in different weather and write down comparisons. Describe how a leaf changes as it gets bigger then gets old.

Questions

When and where do your plants make adventitious roots? These are extra roots from the stems.

Giant pumpkin growers put dirt over the stems so the plants make more adventitious roots. What is the advantage of doing this?

When does your main vine put out a branch?

Does a branch vine grow faster than the main vine? Do you have to measure the entire vine to find this out?

Investigation 7

Plants need light to make food. A new sprout needs to start making its own food before it runs out of the food stored in the seed. How bright does this light need to be? What happens to a sprout if the light isn’t bright enough? Let’s find out.

Question: How does light affect a sprout?

Materials:

Long grow light

5 Styrofoam cups

10 seeds

Potting soil

Pencil

Metric ruler

Plastic wrap

Books or blocks of wood to make steps for the cups

Procedure:

Step 1: Open your science journal and write the date. Put down Investigation 7. Copy Table 1 into your journal.

Step 2: Number the cups 1 to 5 and fill them with potting soil. The soil should be 1.5cm below the top after it is firmed down.

Step 3: Add water to each cup so the soil is damp but not soggy.

Step 3: Measure 2.5cm from the end of the pencil and make a mark. Use the pencil to make two holes 2.5cm deep in each cup.

Each pumpkin seed is planted at the same depth in the same type of cup and potting soil.

Step 4: Put a seed in each hole. All the seeds should be planted the same way. Add potting soil to fill each hole. Cover the cups with plastic wrap.

Step 5: Build steps under the grow light so the top of each cup is 5cm higher than the next one. The grow light should be over the tops of all the cups and only 2.5cm away from the top cup.

Step 6: Turn the grow light on for 12 hours every day. Check for sprouts every day. When sprouts appear, take the plastic wrap off the cup. Don’t let the soil dry out.

Step 7: Describe, draw and measure the length of the stems in centimeters of all the sprouts every day until the first true leaves appear. Write the measurement in Table 1.

As the pumpkin sprouts get farther from the light, they grow taller trying to get to it.

Observations:

Table 1: Length of sprouts

Table 2: Describe the sprouts

Conclusions:

Why do you make all the holes for the seeds the same depth?

Think back to other Investigations and explain why 2.5cm is a good depth to plant pumpkin seeds.

Why should all the seeds be planted the same way?

Is it important to have the light turned on for the first two or three days? Explain why you think this.

Does it matter how close to the light a sprout is? Explain why you think this.

A grow light isn’t really bright enough for a pumpkin sprout even when it is very close. But a sprout does its best to get close.

What happens to sprouts farther away from the light?

Think back to other Investigations you have done. Why is it important for the new sprout to have a short stem?