Summertime Green: Photosynthesis

Green plant in sunlight

This simple experiment will teach kids about photosynthesis.
Image: Shutterstock

If you live in a place that stays green all summer, this is a great little experiment to address two science questions: Why are leaves green? And why do plants need sunlight?

This is an easy one. All you need is some tape, black construction paper, clear plastic bags, and of course, a plant. One with big, broad leaves is best, either inside in a pot or outside in your yard. If you choose one outside, try to pick one that is a bit protected from wind so your sun shield won’t get blown off.

First, cut a piece of black construction paper big enough to cover both sides of one of your plant’s leaves. Wrap it around a leaf and tape it in place. Remember to be careful with this step – if you bruise the leaf you could affect the results of your experiment. If it might rain, cover the paper with your clear plastic bag and tape that on too.

Now the boring part. Wait for exactly two weeks. Don’t take the paper off, even for a peek. What you are testing is what the total darkness does to your leaf.

At the end of the time, carefully take off your sun shield. Compare the leaf you’ve had covered to the other leaves on the plant. It should look sickly, a little pale or dried out. This is because without sunlight, the plant hasn’t been able to make food to feed that leaf, and its chloroplasts, the green parts of the cells, are not able to produce chlorophyll, or plant food. When plants are deprived of light and grow spindly and pale, scientists call them etoliated.

To make this experiment more interesting, repeat the process on various plants around your yard. Do different plants need different amounts of light? What about plants that are already growing in the shade?

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