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UFM A2 Video Clip 1: A class discusses their initial ideas
Several groups in the class present their initial ideas about the motion of a cart that is acted on by a constant strength continuous force. Some think that this will result in a constant speed, while others say the speed will continuously increase. These latter groups use at least three different lines of reasoning to justify their prediction.
UFM A2 Video Clip 2: Group 3 works through STEPS 3 and 4
The group records speed-time data as a fan unit pushes the cart along a single track, and then watch a movie of a similar cart moving along three tracks. They conclude that the speed continually increases, which is no surprise since this is what they predicted.
UFM A2 Video Clip 5: The class discusses Summarizing Question S3
The instructor asks one group about their response to question S3 and then asks the rest of the class for more clarification. Since there is broad agreement, he then briefly discusses how people's initial ideas may have influenced how they actually did the experiment.
UFM A2 Video Clip 6: Group 7 discusses Summarizing Question S5
The group prepares a whiteboard illustrating their response to question S5 about a soccer ball being given a kick. On further discussion, they change their minds about which section to highlight as to where the foot is in contact and where a force is pushing the ball forward.
UFM A2 Video Clip 7: The class discusses Summarizing Question S5
Several groups present their highlighted speed-time graphs. All agree that the two highlighted areas should be the same, but one group's graph differs in exactly which section is highlighted. Other students comment on this graph, but the group with the differing graph does not seem convinced!
UFM A2 Video Clip 8: The class discusses Summarizing Question S6
After responding to a clicker question, most groups agree that the speed of the cart would continue to increase. However, some think the rate of increase would get smaller and smaller, and may become imperceptible. The instructor reminds the class that they only have evidence over three tracks, so this can remain an open question for now.
UFM A2 Video Clip 9: The class discusses the direction of the fan force
The class has just conducted a 'gallery walk' in which they reviewed each group's explanation for why a fan-cart speeds up as it moves along the track. Two groups then discuss what would be the appropriate direction for the force arrow on their diagram. One group bases their argument on what effect the fan has on the air, while the other focuses on the effect it has on the cart. Knowing that 'backward' forces are the topic of the next activity, the instructor decides to leave this issue unresolved at this point.
UFM A2 Video Clip 1: A class discusses their initial ideas