Try This: Falling Leaves
Some trees stay green the whole year round while others lose their leaves in the fall and winter and grow new leaves in the spring. If you've ever seen trees lose their leaves in the fall, you may have noticed that the leaves turn from green to yellow, red, or orange before eventually falling to the ground.
Where do the leaves get their colors?
- 4–5 spinach leaves
- 1 drinking glass
- Nail polish remover — ask a parent for help in getting this
- Coffee filter
Tear the leaves into small pieces.
Place the pieces into the bottom of the glass and mash them together with a spoon.
Add several teaspoons of nail polish remover to the leaf mush. Wait until the leaves settle at the bottom of the nail polish remover. If the remover does not cover all the leaves, add enough so that they are totally covered.
Cut a rectangle from the coffee filter. It should be slightly narrower than the glass.
Tape the rectangle to the pencil and, when the leaves are settled, place the pencil across the top of the glass so that the coffee filter rests in the nail polish remover without touching the leaves.
Let the glass sit for several hours.
You should see many colors work their way up the coffee filter. The green you see comes from the chemical that makes leaves green — chlorophyll. But you should also see other colors, like red, yellow, and orange. These come from different chemicals that are also found in green leaves.
Autumn is a second spring when every leaf is a flower.
— Albert Camus, French novelist
During the spring and summer, photosynthesis produces so much chlorophyll you can see only the green color in the leaves. But as the days get shorter, less chlorophyll is produced and the green fades away so that you can finally see the other colors. When the green is gone, the leaf is not far from falling to the ground.
When fall comes, watch the leaves change color. Can you tell what causes this to occur?
Words to Know
chlorophyll: the chemical in plants that makes their leaves green.
photosynthesis: the process by which plants turn sunlight and water into chlorophyll.
Chlorophyll absorbs red and blue light and reflects green light back to your eyes.
KIDS' LAB LESSONS
QUESTIONS Do seeds need light to grow? Do plants need light to grow?
EXPERIMENT OVERVIEW You've already seen what happens to some trees when they don't get enough light — they lose their leaves. But plants and trees are different.
In this experiment, you'll get to explore whether or not seeds and plants need light to grow by placing some seeds and plants in the dark while others stay in the light. You will decide whether or not light makes a difference in their growth pattern.
This experiment will take a few days since most processes with plants occur very slowly, but the results should be obvious and a little surprising.
SCIENCE CONCEPT Most gardeners believe that light and water are the basic needs of any plant. You'll test that theory by letting some seeds grow in a dark setting while others grow in a light setting. You'll then take two healthy plants and place one in a dark closet for a few days while the other sits in the sunshine.
By doing this you will be using one of the most important pieces of the Scientific Method — testing one change at a time. It's important that you treat the seeds and plants exactly the same except for where they are placed. By doing so, you will know whether light makes a difference.
- 2 paper towels
- 2 small dishes
- Pinto beans (available at a grocery store)
- 2 small, identical, healthy potted plants
Fold the paper towels so that each fits onto a dish.
Place the folded paper towel on a dish and place several beans on each paper towel.
Pour just enough water onto the paper towel so that it is damp. Pour out any excess water from the dish.
Place one dish of beans in a closet where it will stay dark for several days.
Water the potted plants until their soil is just damp and place one of the plants beside the beans in the same dark location.
Place the second dish of beans in a well-lit place alongside the second plant.
After two days have passed, slightly dampen the two dishes containing the beans and water the potted plants. Make sure that you give each the same amount of water so you keep the experiment fair.
After a total of four days have passed, take the beans and plant out of the closet and place each by its sunlit partner.
QUESTIONS FOR THE SCIENTIST
Which sample of beans grew better — the one in the dark or the one in the light?
Which sample of potted plant grew better — the one in the dark or the one in the light?
If you were going to plant seeds, where would you put them — in a light place or in a dark place?
Think about the amount of light where seeds and plants normally grow. Does this experiment confirm that those locations are the best places for growing?
Do some seeds require different amounts of light? Experiment with different kinds of seeds and amounts of sunlight to see what factors most affect germination and growth.
Can you find your way through all the tiny tubes in this leaf from START to END?