# 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.

# OS6 Burying Seeds

Directions on seed packets usually tell how much dirt to put over the seeds. Some gardeners say to only plant a seed as deep as it is tall. Is this important? Let’s find out.

Question: Does it matter how deep a seed is buried?

Materials:

10 pumpkin seeds

5-16 oz. planting cups

potting soil

metric ruler

plastic wrap

Procedure:

Step 1: Open your science journal. Write the date and Investigation 6. Copy Table 1 into your journal.

Step 2: Number the cups 1 to 5. Mark each cup with a little line at 4cm, 6.5cm, 9cm, 11.5cm and 14cm from the bottom.

Step 3: Put 4cm potting soil in each cup. Be sure this is pushed down firmly and still 4cm deep. If you hold the cup up with a light behind it, you can see the dirt is level with your first mark.

Step 4: Lay two seeds on the dirt in Cup 1

Step 5: Put 2.5cm potting soil in each cup to the 6.5cm mark, pushing it down firmly

Each cup must be labeled. Each layer of soil is added and one cup is planted until all are done.

Step 6: Lay two seeds on the dirt in Cup 2

Step 7: Put 2.5cm potting soil in each cup to the 9cm mark, pushing it down firmly

Step 8: Lay 2 seeds on the dirt in Cup 3

Step 9: Put 2.5cm potting soil in each cup to the 11.5cm mark, pushing it down firmly

Step 10: Lay 2 seeds on the dirt in Cup 4

Step 11: Put 2.5cm potting soil in each cup to the 14cm mark, pushing it down firmly

Step 12: Lay two seeds on the dirt in Cup 5

Step 13: Add water to all the cups so the soil is damp but not soggy. Cover the tops with plastic wrap. Set the cups in a warm place.

A hook and cotyledons is pushing up out of the soil of the cup.

Step 14: Check the cups every day for pumpkin sprouts. Take the plastic wrap off when the sprouts appear.

Step 15: Count seven days after the first seeds germinate or when the seeds planted the deepest appear, carefully dump each cup out and look at the seeds.

Observations:

The radicle must push down into the soil to start the pumpkin root. Exposed on the surface it can dry out before it gets into the moist soil.

Describe the sprouts when you take them out of the cups:

The seeds are trying to grow in the various cups labeled 1 to 5.

Conclusions:

What is the best depth to plant the pumpkin seeds? Why do you pick this depth?

Can seeds be buried too deep to grow? Why do you think this?

Taken out of the cups the seedlings are arranged from top of the soil on the left to the deepest on the right.

Does the size of the seeds matter? Why do you think so?

# OS2 Germinating Seeds

Investigation 2

What’s In a Pumpkin Seed?

Although many creatures eat seeds, the number one reason a plant makes seeds is to grow new plants. Each of the three main parts of a seed has a purpose. Let’s look at these parts and see how each accomplishes its purpose.

Note: Part of this investigation is difficult to do. You may want an adult to use the paring knife to avoid cutting yourself.

Question: What are the three parts of a seed?

Materials:

3 Pumpkin seeds

Metric ruler

Cup of warm water

Custard cup

Paring knife

Magnifying glass

Procedure:

Step 1: Open your Science Journal, write “Investigation 2” and the date. Draw Table 1 in your journal.

Measuring the dry seeds is important so we will know if soaking makes a difference.

Step 2: Measure the length, width and fatness of Seeds 1, 2,and 3 in millimeters. You can use the same method you used in Investigation 1. Record the measurements in Table 1.

Soaking the pumpkin seeds makes them softer and easier to take apart.

Step 3: Mark 1, 2 and 3 at different spots on the custard cup. Pour water in it and put the 3 pumpkin seeds in the water by their numbers to soak until the seed feels like it has air under the surface and bends a little [about an hour].

Step 4: Take Seed 1 out of the water and dry it. Mark its length, width and fatness below the first marks.

After the seeds soak, measuring them again shows if they have changed.

Step 5: Take the seed coat off. You may have to cut the tip off with the paring knife. Try to tear the coating. Describe how it feels on the outside and the inside.

Step 6: Look at the inside of the seed. Is it one piece or two? How does it feel? What color is it? The two pieces are called cotyledons or seed leaves.

Step 7: Use the paring knife to cut the blunt end off the cotyledons. Use the paring knife to carefully pry them apart. What do the insides of the cotyledons look like? What do you see at the sharp end of the cotyledons?

Step 8: It’s very hard to do these steps well so repeat them with the other two seeds.

Observations:

Measure the beginning and ending length, width and fatness of each seed. Write the measurements in the table.

Table 1:

Draw and describe the three parts of the seed: the seed coat, the cotyledons and the plant embryo.

Like all seeds, a pumpkin seed has three main parts. Can you spot them?

Analysis:

Subtract the ending measurement from the beginning measurement for the length, width and fatness of each seed.

Conclusions:

Did the length, width or fatness of the seeds change? Why do you think this is the case? Why is it important to know if these change?

Do you think three seeds is a big enough sample? Why?

Why did we soak the pumpkin seeds before trying to cut them open? [Try cutting a dry one open.]

These are the three parts of a pumpkin seed. The cotyledons contain endosperm a form of starch found in all seeds although all don’t have cotyledons.

What do you think each part of the seed does?

When you buy roasted pumpkin seeds, sometimes the seed coats are removed. Why?

# OS1 Seed Sizes

Investigation 1

How Big Is a Pumpkin Seed?

It’s easy to say all seeds for one kind of plant are the same. They do grow into the same kind of plant. They do look a lot alike. Let’s look at some pumpkin seeds. Are they really all the same?

Question: Are all pumpkin seeds the same size?

Materials [What you need]:

10 Pumpkin seeds

Custard cup

Metric ruler [Scientists use the metric system.]

Piece of paper and a pencil

Science Journal

Procedure [How to do this investigation]:

Step 1: Open your Science Journal, write “Investigation 1” and the date. Then copy Table 1 into your Journal.

Step 2: Write down the kind of pumpkin seeds you are using.

Step 3: Dump ten pumpkin seeds out on a piece of paper.

Step 4: Pick out a pumpkin seed and draw it in your science journal. Describe the pumpkin seed. Is it shiny? Is it smooth? What color is it? Is the edge smooth? Is the edge the same all the way around? What does it smell like?

Step 5: Label a place ‘1’ on the paper. Put a pumpkin seed under this and draw a short line above and below the seed and on each side at the widest place. Put the pumpkin seed in the custard cup.

Take one seed and put measuring marks on the paper. Be sure to put the seed in the custard cup when you are finished so each seed is done only once.

Step 6: Repeat Steps 4 and 5 with another pumpkin seed but label this one ‘2’.

Step 7: Keep repeating Step 6 until you have done all 10 pumpkin seeds labeled 1 to 10.

Each pumpkin seed has a mark above it, below it and on each side.

Step 8: Starting with the pumpkin seed 1 marks use the metric ruler to measure how many millimeters long the seed is. Write it down under the marks and label it ‘L’. Then measure how wide pumpkin seed 1 is, write it underneath and label it ‘W’.

Step 9: Do the same for pumpkin seeds 2 to 10.

Step 10: Write the ‘L’ measurements in Table 1 in your Science Journal for each seed.

Step 11: Write the ‘W’ measurements in Table 1 in your Science Journal for each seed.

All the measurements are in millimeters. Write each one down for each seed.

Observations [What you see]:

Kind of Pumpkin Seeds:

Draw and describe a pumpkin seed:

 Table 1 Seed Length Width 1 2 3 4 5 6 7 8 9 10 Total Average

Analysis [Finding the size of an average seed]:

Step 1: Add up all the lengths and write it in the Table.

Step 2: Add up all the widths and write it in the Table.

Find the average size of a pumpkin seed by adding up the column of measurements then dividing by 10, the number of seeds.

Step 3: Divide the total lengths by 10 [the number of seeds]. This is the average length. Write it in the Table.

Step 4: Divide the total widths by 10 and write the average width in the Table.

Important Note about dividing: You only measured the seeds to a whole millimeter so the average length and width can only be a whole millimeter. If your quotient (answer) has a decimal, you should round it to the nearest whole millimeter. Your answer can not be more accurate than your original measurements which were in whole millimeters.

Looking at the Seed Averages another way using a graph:

Step 1: Get a piece of graph paper. Label the x-axis (the one across the bottom) “Seeds” and number the lines 1 to 10 for the seeds.

Step 2: Label the y-axis (the one that goes up) “Size in mm” and number it from 0 (at the corner) up for millimeters

Step 3: Count up the y-axis to the average height of a pumpkin seed. Draw a line across at that average.

Step 4: Put a dot for the height of 1 above the 1, height of 2 above 2, all the way to 10

Step 5: Repeat Steps 4 and 5 for the width of the seeds (Use another color.)

Some seeds are a little bigger, some a little smaller but all are close to the average on the graph.

Conclusions [Thinking about the investigation]:

Did all the seeds look a lot like the one you drew and described?

Why would all of this kind of pumpkin seeds look a lot alike?

Were all the seeds the same size?

Look at your graph to see how the dots compare to the line. Were most of the seeds close to the average size?

Why do you think most seeds are close to average size?

Why measure ten seeds to get the average size?

Would measuring more or fewer seeds give a better average? How many is enough?

Take 2 more seeds out of the packet and measure them. Are they close to the average size?

Why would scientists use an average size?

Do you think seeds from another pumpkin of the same kind as these seeds would be about the same size as these? Why?

Do you think seeds from a very big or very small kind of pumpkin would be the same average size? Why? Try measuring seeds from other kinds of pumpkins and find out if your hypothesis [idea] is correct.

Was this an accurate way to measure the length and width of the seeds? Explain why you think so. Can you think of a better way? Try your method and compare your results. Does it change your conclusions about seed size?