Today we started forces, and I tried the new Interaction Stations from Kelly O’Shea (@kellyoshea) and Brian Frank (@brianwfrank) on twitter… their blog posts are below.
First we reviewed the Bowling Ball activity from last class, and I assigned the comic strip for homework, where they will detail the four main actions (speeding up, slowing down, staying at rest, staying at a constant velocity) in comic panel form.
Next, we jumped into the Interaction Stations. I told the kids to look for two objects to focus on, and describe the evidence of compression, stretch, or shear. I simplified the stations on the bristles of the brush to have one with the buggy pushing the bristles and they bent backward, and one pushing a mass across that bent the bristles forward (which ended up being a great discussion later of friction).
This was excellent, and did not take very long. Some kids for the shearing one said, “Isn’t this also compression?”. Brilliant. This activity was awesome, and then we went through a little bit of the discussion from Preconceptions in Mechanics. We didn’t need to do as much of that after the stations. They were totally getting it.
We also started in this discussion to talk about a force being an interaction between two objects (no push or pull stuff here). This is the way I started it last year, really focusing on BOTH sides of the force coin, and I can’t believe I did it any other way. This is the focus of one of our NSTA presentations for Atlanta!
We also pulled each other with spring scales, and many were surprised that the person who “wasn’t pulling”, was actually pulling. We also interlocked toothbrushes to look at the bristle movement. We have already started hammering home that EACH party exerts/feels the SAME amount of force.