We realized that some students were confused about Bernoulli’s principle based on their two explanations. We focused our whole-class discussion on providing a logical explanation for the two demonstrations. We provided the initial driving question: “What is air composed of?” Then, students discussed the driving question in small groups before the conversation was opened to the whole class. From prior experiences, students knew that air is made of carbon dioxide, oxygen, nitrogen, and other trace gases. Students used their science knowledge to think through the idea that blowing between two objects removes all of the air in that area. For example, students recognized errors in their thinking because air expelled from the lungs contains air molecules (e.g. oxygen, carbon dioxide, etc.). Thus, students were able to refute the idea that the paper tent would collapse and the soda cans move together because of the absence of air molecules relative to the surrounding air. To move the discussion along, we provided scaffolding by asking students probing questions such as, “What is happening to the molecules in the air when we blow through the straw” and “What are molecules doing in the surrounding air?” All students decided that blowing creates a “stream of air molecules” that are all moving in the same direction. At this point, all students were beginning to connect that there are differences in what is occurring with air molecules in a “stream of air” and the “surrounding air.”