When students use plants to investigate cellular respiration, they confront the misconception that plants only "perform" photosynthesis (Driver et. al., 1994). Because this is such a strong misconception, several experiences with plant respiration are needed before students accept the idea that plants use some of the food from photosynthesis. Part of the problem is that students believe that plants are static creatures that do not require energy because they are generally non-motile. This article describes classroom exercises that use an inexpensive respirometer made from a plastic pipet to demonstrate that plants convert some of the food from photosynthesis into carbon dioxide and water as a result of cellular respiration. After students collect data, they present their findings and explain what happened during their experiment. By the time they finish the labs and presentations, students spend so much time discussing plants that have given off carbon dioxide that they begin to reshape their ideas about how matter and energy cycle in nature. (Contains 1 table and 3 figures.)