Research suggests that students have both productive ideas about and difficulties with Newton’s second law. What are some of their ideas?
July 2, 2018
What did you observe in this episode? Talk to your partners about what you saw.
Summarize Chris’s ideas about how the acceleration will change when the mass of the cart increases.
Chris says the acceleration graph will stay the same (line 15), and also says that the acceleration will take longer to get going (line 34). Do you think he is expressing different ideas about the acceleration at these two different points in the episode, or is there a way to make sense of these ideas as describing one way of thinking about acceleration?
Summarize Ben’s ideas about whether the acceleration of the cart will change. How do his ideas differ from Chris’s ideas?
Alanna asks Ben and Chris, “But if the velocity changes, doesn’t the acceleration change? Because the acceleration is the change in velocity” (line 36). What point do you understand her to be making?
What does this episode suggest about students’ ideas about Newton’s second law?