NextGenPET Instructor Resources

To show and then play a video clip, click on the arrow or the video clip title/description. Repeat to hide it.

UFM A4 Video Clip 1: Two students discuss their initial ideas about friction

Erin and Dianne discuss whether they think friction is a force or not, and whether an object would still slow and stop if there were no friction. Erin suggests this could only be checked with a computer simulation.

UFM A4 Video Clip 2: Three students give their views on whether friction is a force

After their class responds to a clicker question, three students give differing views as to whether friction should be regarded as a force or not.

UFM A4 Video Clip 3: Students in another class discuss whether friction is a force

After this class responds to a clicker question, again students give differing views as to whether friction should be regarded as a force or not.

UFM A4 Video Clip 4: A class discusses their ideas about representing friction on a force diagram

Some show friction as a 'backwards' force, whereas others were not sure how to represent it. Though some drew upwards arrows to represent it, they explain that this is not necessarily an indication of a directional force, but just showing where it is acting.

UFM A4 Video Clip 5: Another class's ideas about representing friction on a force diagram

After students have displayed their force diagrams from the Initial Ideas section, the instructor notes that there is consistency between their earlier discussion (Video Clip 3) and their diagrams. He then asks groups with three different representations to explain their thinking.

UFM A4 Video Clip 6: A group works through Exploration #1

The group performs the experiments and concludes that, since the graphs produced by the fan and the friction pad are similar, it is appropriate to think about friction as a force that acts in the opposite direction to the motion.

UFM A4 Video Clip 7: A group performs the experiments in Exploration #2

This group launches a wooden block across various surfaces and measures the distance it travels before stopping.

UFM A4 Video Clip 8: A group discusses how friction works

After examining the sandpaper, block, and table, the group discusses the role of imperfections in the surfaces in providing backwards forces on a moving object, just like the sticky notes do.

UFM A4 Video Clip 9: The class responds to question S1

Ben says that the speed-time graphs produced when the fan and friction pad were used to slow the cart were very similar. Deb then uses that idea to infer that the frictional force must have been acting in the opposite direction to the motion, just as the fan was.

UFM A4 Video Clip 10: Two groups discuss question S2

Both groups express the idea that the sticky notes serve as a larger representation of how the sandpaper and table slow the block.

UFM A4 Video Clip 11: A group discusses question S4

The group first decides that there must still be friction acting on the cart that has no friction pad, because its speed is decreasing. Nancy points out that this is explicitly stated in a footnote in the activity. They then discuss how to draw an arrow on the diagram to represent this.

UFM A4 Video Clip 12: Two groups discuss question S5

Liz first says that the rocket will stop, but the others suggest it would keep going because no forces are acting on it. Linda even uses the movie 'Gravity' as an example. In the second group, April paraphrases Newton's First Law to justify that the speed would not change, and also explains more fully. Beth remarks why this idea seems non-intuitive.