Week 9 Reflection (And Examples for Assessment 2 Part 3)

Week 9 concluded the investigation of how balanced forces don't change motion, how unbalanced forces do change motion, and how a change in motion depends on the mass of the objects.

My students had a ton of different ways to investigate this, some of the ideas that generated the best data are described below:

Tug-of-war: This was a popular one as a lot figured out that they could easily combine balanced, unbalanced, and mass together (they generally went with the reasonable assumption for 8th graders that more mass generally equaled more ability to pull). Most measured whether they were able to pull the other side, others looked at how long it took to shift to the direction with more mass.

Bottles and Ramps: A number of students filled water bottles with different amounts of water, they looked at how long it took different masses of water to go down ramps of different heights. Some of the conclusions, such as balanced need to be more inferred, but there were a lot of variables that they students easily changed. (Other students looked at toy cars with different masses for this.)

Toy Cars: There were a lot of ideas with toy cars, but one of the most successful looked at crashing together cars of different or the same mass together and seeing the bounce back. 

Balloon Powered Car: Some students experimented with the cars, I didn't make this a requirement, but students tried things like adding balloons pointing opposite directions and blowing the balloons up different amounts to change balanced and unbalanced forces. Weights were also added to the cars to change mass.

Those were just a few of many different set ups. There were others that were super creative, but didn't quite reach all the targets to investigation. While I approved all the plans before they started, I really didn't want to stop students from investigating something in a creative way just because the data wouldn't be perfect.

This week we also moved on to part 4, the bumper. Only some of my students are at this step, others are still working on their slides (revising) or their write up from the investigation. To save time, and because I only have so many planks of wood, I provided a set up to test the impact. The students did have the options to try something different, but this set up worked for most.

There was a ramp for the car to go down and a short distance away a book for the car to collide to, depending on the car the height of the book might have changed.

 

The students measured how far a penny moved after colliding with the book, for some the penny shot off of their car, for others they measured the distance it moved on the car itself. Their challenge was to reduce significantly the amount it moved, with a goal of zero. Given that the amount of movement depended a lot on how good their car was, I didn't have a specific requirement as that would put more difficulty on those who had better cars.

Stayed on the car, so distance measured on car

Other pennies flew off of the car

Others hit with too much force that they began to go over the book, this one would probably retest with a stack of two books to prevent this

All in all the assessment is going well. I think my students really will benefit from some more structured in their seat activities as there has been a lot of collaborative work recently. Collaborative work is never a bad thing, but a mix of activities can be good. Next week we will be working on some more structured group activities, partly to not introduce the new task in the two days before break, but also because I think they need the mix.