Flowers Unit: Simple Plant Respiration Experiment

This experiment is designed to teach your child about one of the important jobs leaves do for plants. Leaves are extremely important to all plants because they make the plant’s food.

That’s really different from you and me—if we want food, we have to grow it or go to the market and buy it and then we have to cook it and eat it. But plants do it all in their leaves!

The leaves breathe in a gas called carbon dioxide and absorb energy from the sun to be able to do the work of making food. This process is called photosynthesis. (That’s a fun word! See if your child can say it!)

One thing the leaf doesn’t need when it makes its food is a gas called oxygen, so it expels it. This is called respiration. Let’s try an experiment to help your child understand one part of this process. (It’s going to take a few hours to complete this experiment, so start it early in the day.)

What you need:
  • small bowl or jar of water (a clear bowl or glass is best)
  • a straw
  • a few fresh leaves
  • magnifying glass (optional)
What to do:

First, let’s connect how we breathe with plant respiration. Have your child take a deep breath. Explain that when we breathe in, we take in oxygen. When we breathe out, we release carbon dioxide. Plants do the opposite—they breathe in carbon dioxide and breathe out oxygen.

Next, set up your bowl of water and give your child a straw. Have them take in a deep breath, then blow it out into the water through the straw. They should make lots of bubbles. Ask them what the bubbles are made of (air, specifically carbon dioxide). How did the bubbles get into the water? (They respirated or exhaled them out!)

Next, let’s see how leaves can do the same thing. Submerge a freshly picked leaf completely under the water in your bowl. Put the bowl in a sunny spot, and let it sit for a few hours. (Work on the other activities in our Flower Unit while you wait!)

When you come back a few hours later, have your child observe how the leaf has changed. They should see lots of tiny bubbles on the leaf and the edge of the bowl. If you have a magnifying glass, let your child take a closer look. Where do they think these bubbles came from? They are from the leaf breathing out! You can explain that the leaf’s bubbles are made of oxygen.

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