Chlorophyll is the green pigment in leaves that captures sunlight to make food for plants. You can test how light color affects this process by placing elodea under red, blue, green, yellow, and white cellophane filters hung in front of a lamp. After 16 hours, the results are striking: red and blue light each produced 1 mL of oxygen, while green produced no measurable oxygen at all.

Chlorophyll is the green pigment that captures sunlight to make food for plants — but it needs light to do that job. When you clip cardboard shapes onto leaves of a living plant, those shapes block sunlight from reaching that section of the leaf. After four days, remove the shapes and compare the covered areas to the rest of the leaf. Without sunlight, photosynthesis cannot run in those spots, and the green fades.

Chlorophyll is the green pigment that captures sunlight to make food for plants — and all summer long, it hides other colors in leaves. You can separate these pigments yourself using chromatography, a method that splits mixtures by how fast they travel. Tear leaves into small pieces, soak them in rubbing alcohol, then dip a strip of coffee filter paper into the colored liquid. As the alcohol travels up the paper, it carries each pigment a different distance, revealing bands of green, yellow, and sometimes orange or red.