Carbon Dioxide
Carbon Dioxide is a gas that plants pull from the air and turn into food through their leaves.
Think of it this way
A glass jar sits open on the counter. Tiny dots of carbon dioxide float in the air all around it. A green leaf inside the jar slowly pulls those dots in through small holes on its surface. The leaf uses those gas dots, plus water and light, to make sugar stored right inside the leaf.
Explaining carbon dioxide by grade level
Plants need Carbon Dioxide the way you need food. They take it in through tiny holes in their leaves. Inside the leaf, they use sunlight to change it into a kind of sugar. That sugar is what helps the plant grow big and strong.