Carbon Cycle

Carbon Cycle Worksheet For Kids

The carbon cycle worksheet for kids explains how photosynthesis recycles carbon in nature and the role of plants and animals.

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MatchCard Science Carbon Cycle Worksheet

Objective: Describe the carbon cycle.

MatchCard: Download below.

MatchCard Information Pieces are placed on the MatchCard to demonstrate oxygen and carbon dioxide in respiration and the synthesis and breakdown of starch.

Download the Carbon MatchCard

This is MatchCard #11 of the Botany Unit Study. Find more information on MatchCard Science below.

Let's Learn About the Carbon Cycle

This lesson demonstrates one of the important ways that plants and animals interact in their environment.

Carbon is an atom that has four electrons in its outer shell. (It has a total of six electrons, two in the inner shell.) Carbon is called the backbone of living material. Carbon is recycled by plants and animals and is necessary for survival.

Before Getting Started

Before presenting the information in the Carbon Cycle MatchCard, do the first part of the project listed below. While you are waiting for the pickling lime and water to settle, you can present the information below.

Plant Production

Plants produce two important substances:

1. Oxygen
2. Starch (also called glucose or sugar or carbohydrates)

Oxygen (0₂) and starch (C₆H₁₂O₆ ) are produced by photosynthesis in the leaves of the plant.

Start this lesson by reviewing the photosynthesis lesson with your kids.

They can play the game to see how quickly they can form oxygen and glucose molecules from the water and carbon dioxide.

Then they will be ready to find out what happens to the oxygen and glucose that the plants make.

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Oxygen

So what do we do with the oxygen that plants make? We breathe it in. So do all animals.

Put the Information Piece with the picture of human lungs on the card to the left of the tree. We inhale oxygen.

What do we exhale?

Give students a chance to guess. Let them take several breaths in and out. Seems like we're breathing the same amount in and out, doesn't it. The volume of air is about the same, but the chemical composition is different.

You inhale oxygen and exhale carbon dioxide. The carbon dioxide is made by your cells. You breathe in order to give your cells the oxygen they need, but also to exhale all that carbon dioxide they made.

You might even compare it to bringing in bags of groceries for food, and taking bags of trash out of the house. Your cells need oxygen to come in and carbon dioxide to go out. The lungs are doing that for us.

Note: To be accurate, the air you breath is approximately 79% nitrogen and 21% oxygen. The air you exhale is approximately 79% nitrogen, 16% oxygen, and 5% carbon dioxide. Students at this point do not need to know those amounts. But they do need to know that air is made up of a number of substances. And we inhale oxygen for our cells and exhale the carbon dioxide the cells made.

So what happens to the carbon dioxide? Give them a chance to answer. Prompt them with the Photosynthesis Matchcard if they don't remember.

Yep, that's it. The plants need the carbon dioxide so they can convert it to oxygen.

Plants make oxygen for animals from carbon dioxide. The animals make carbon dioxide for the plants from that oxygen.

We've got a pretty good thing going, huh? It gets better.

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Starch

Remember that the plants also produce starch, or carbohydrate, or glucose, or sugar. There are some technical differences between the ways those four terms are used, but you should be aware that they are all the chemical C₆H₁₂O₆ .

By the way, can you see from the chemical formula why it is called carbohydrate. (Carbon and water)

Let's list carbohydrates:

• Grains
• Fruits
• Rice
• Bread and Pasta
• Desserts

Where do these all come from? (Plants)

So what happens when you eat the carbohydrates? The cells of your body turn the carbohydrates into carbon dioxide and water.

Does that sound familiar? It should; because it is the opposite of photosynthesis.

You could almost think of the cells of our body and the cells of animals as anti-photosynthesis machines. We take oxygen and carbohydrates and produce carbon dioxide and water.

You and the Carbon Cycle

So what's your role in all of this?

• You inhale the oxygen from the plants.
• You eat and digest the carbohydrates from the plants.

Eventually the oxygen and carbohydrates find their way to each cell of your body.

• You eliminate carbon dioxide by exhalation.
• You eliminate water both by urination and exhalation.

Chemical Formula Activity

Use the nickles, and dimes, and pennies that you used in MatchCard #6 for photosynthesis and let the kids reverse the chemical equation.

Science Project with Carbon Dioxide

Calcium hydroxide (which is in pickling lime) will detect the presence of carbon dioxide. We can do a little experiment to detect the presence of carbon dioxide in our breath when we exhale.

• Add one teaspoon pickling lime to a small plastic zip bag.
• Fill the bag with water.
• Carefully expel all the air from the bag.
• Shake and let your carbon dioxide testing solution set for a few hours.
• Very carefully, insert a straw into an opening of the bag just large enough for the straw. Keep your finger over the end of the straw to prevent air from getting in.
• Exhale into the bag. Close the bag quickly and shake.

The cloudy color indicates carbon dioxide from your lungs.

Botany Science Experiment
You can set up an experiment using larger bags to detect different amounts of carbon dioxide more readily. Use a one gallon bag and one tablespoon of pickling lime. Compare when you have taken a big deep breath of fresh air and when you have re-breathed your own breath for a minute.

Try it with fresh air. Try it after you have been in a crowded, closed-in room.

Do you see any differences?