This is a fool-proof lab to demonstrate photosynthesis and respiration in aquatic plants. This lab works great when teaching about the carbon cycle as well. In this lab students will learn that plants only do photosynthesis in the light and in the dark cellular respiration occurs. Materials needed (per group): 4 test tubes with lids or parafilm, water, bromothymol blue, straw, elodea or other aquatic plant, test tube rack, aluminum foil, light source, and a goldfish is optional for an extension