Developing a Better Understanding of the Relationship Between Transpiration and Water Uptake in Plants

Performance on a multiple-choice item in a public examination indicates that most students do not understand the principle of the bubble potometer and its limitations in measuring transpiration rate. Teaching strategies are suggested to overcome these problems by helping students to compare the bubble potometer with the weighing method, develop the concept of assumptions, and resolve cognitive conflicts. To rectify the alternative conception on the role of transpiration, an interactive activity is designed to guide students to expose their preconceptions, design investigations to test them and evaluate the validity of the original ideas.