Adapted from "Scholastic
News," February 1993.
Imagine you're a
plant and you're about to drop your seeds. Wherever one hits the ground,
a new plant will grow.
Think: do you want
your seeds to fall close to you or far away? (Hint: all plants
need soil, water, sunlight, and space to grow. Will your sprouting seeds
get more of these if they're bunched together or far apart?) If you're
like most plants, you want to scatter your seeds around. But how? (After
all, as a plant, you're rooted to the spot.) Test your seed-sending skills
with these experiments.
seeds in these places:
- Supermarket shelves:
Dried beans and popcorn are seeds. So are nuts like pecans.
- Gardening sections:
Look for packets of planting seeds.
- Inside fruits:
Collect ripe apples, oranges, cantaloupes, pumpkins, bell peppers, etc.
Cut the fruits open and carefully remove the seeds. Wash the seeds and
spread them on a paper towel. Let them dry on a sunny windowsill for
- Schoolyard: Just
look around! If you don't see any try this: Pull on an old sock over
your shoe. Walk in a grassy or wooded area for five minutes. Remove
the sock carefully and check it for tiny seeds.
do seeds travel?
1. Gather five seeds
of different sizes and shapes.
2. Describe your
seeds on a chart.
3. Next to each
seed description, predict whether that seed could travel by wind, water,
4. Try out your
predictions using the tests below. Record your answers on the chart.
- Wind Test: With
an adult's help, stand a fan on a chair so that the top half sticks
over your desk. Use tape to make a starting line 25 cm (10 in.) away
from the fan. Place seeds on the starting line. Turn the fan on at medium
speed for 20 seconds. Measure how far your seeds traveled. A seed passes
the Wind Test if it blows more than 1 m (40 in.) away from the line.
- Water Test: Fill
a small container half full of water. Drop the seeds into the water
and stir. A seed passes the Water Test if it floats.
- Hitchhiker Test:
Place a seed on a table and cover it with one test material. Gently
press down on the material with your palm. Lift and check -- does the
seed stick to the material? Repeat with two other test materials. A
seed passes the Hitchhiker Test if it sticks to any test material.
Were you surprised by any of the ways your seeds could travel? Look
at the seeds that passed the Wind Test. How are they similar? (Hint:
Are they all small? Big? Do they have the same shape?) How are these
seeds different? What do the floating seeds have in common? How about
the hitchhiking seeds?
What helps a seed travel in the wind?
1. Choose a seed
that did not pass the Wind Test. Find a second seed of the same kind
and size to be your control seed.
2. How can
you change your seed so that it could travel in the wind? Brainstorm
a list of ideas. (Hint: What do the best wind-traveling seeds have
in common?) Think about the seed's:
- density (how
heavy something is compared to its size)
- what else?
one idea from your list. Make that change to your seed.
4. Give both
your changed seed and your control seed the Wind Test. Which moves
- If the control
seed moves farther: Undo the change on your other seed. (That will
make both seeds the same.) Pick a different idea from your list
- If the changed
seed moves farther: Your change is a success! Add it to your control
seed too. Then make a new change to your winning seed.
step 4 until your changed seed passes the Wind Test.
Compare your seed design to others in the class. What do they
have in common? What change seemed to help our seed the most?
Which helped it the least?
Combine the best ideas in your class to design a seed that's a
champion wind traveler.
Will a seed travel just as well in any environment? Why or why not?
1. Choose a seed
to adapt. Find a control seed that matches it.
2. Read your
Environment Card. What are some ways a seed might travel in your
environment? How couldn't a seed travel there?
changes that might help your seed travel in its environment. (Remember:
Your seed has to pass both tests on your Environment Card.)
4. Choose one
idea from your list. Make that change to your seed.
5. Put your
seed (and the control seed) through both of the tests listed on
your card. How well do they do?
- If the control
seed is better at both: Undo the change on your other seed. (That
will make both seeds the same.) Pick a different idea from your
list to test.
- If the changed
seed is better at both: Your change is a success! Add it to your
control seed too. Then make a new change to your winning seed.
- If there's
no clear winner: Did each seed win in one test? Then the next step
is up to you. Decide which seed design you think holds the most
promise. (Keep a sketch of the other design. Scientists sometimes
hit a dead end, and have to go back to an earlier design.) Give
both seeds the design you like. Then make a new change to one seed.
step 5 until you have a seed you know will succeed in your environment.
7. Draw a
diagram of your seed, label the materials you used to adapt your
seed, and explain how your seed can disperse (scatter) in your
Compare your seed with others from your class. Can you guess which
seeds share the same environment as yours? Switch Environment
Cards with another group. How would your seed do in this new environment?
the environmental conditions of your schoolyard. (Is there much
wind? Do many animals visit?) Design a seed that could travel
easily in your schoolyard.