How does air pressure work to give a balloon its shape and size?
Think about this for a moment and then draw your ideas on paper.” Ask several students to share their drawings with the class. (Try to get a variety of models on the board unidirectional models, omnidirectional models with arrows, etc.) Note to Teacher: Presumably students will use arrows to depict air pressure in their models. Do not address this issue yet. RECAST Thinking Step 2: Considering What Different Models Emphasize Put the following air pressure models on the board if they are not already represented in students’ models: Model A Model B Model C Note to Teacher: The models above are not relational because they do not show the air pressure inside of the balloon compared to the air pressure outside of the balloon. For now, focus on what is happening outside the balloon with the dots versus arrows models of air pressure, so that the students understand the distinction between them. Introducing students to relational causality is the focus of Section 3. Ask: “Which model do you th
