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.
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.
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.
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.
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.)
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?