Video narration
What is your houseplant getting from a sunny windowsill: food, or something else? Sunlight isn't food; it powers the leaf. Photosynthesis is how a plant uses light: roots bring up water, while leaves take in carbon dioxide, a gas in the air. The leaf turns those ingredients into sugar the plant can use, releasing oxygen along the way. So your sunny-window plant makes sugar from water and carbon dioxide, powered by sunlight, and releases oxygen.