06 summer - carey, anne, casey
conservation of energy, sans friction

We incorporated a prediction cycle, similar to the pendulum prediction cycle, regarding a marble going down hot wheels track. We had different levels of implementation of this, in the end, due to a combination of our different access to materials and what we were attempting to show with the demonstration. In Casey’s demonstration, he measured the velocities at the end of the track (at the same elevation) intending to show that the energy is conserved as well as that the energy is transferred to kinetic energy in the steeper one due to the decrease in gravitational potential. Anne, merely attempted to show the latter, which worked well, as conservation laws are difficult to prove quantifiably. We both agree that it’s a valuable exercise, we were just trying to do different things with it. We added it in because our previous example, a skier on a slope or a halfpipe, was theoretical, but this was something students could see and wrestle with as they adjusted their schemas with this potentially “discrepant event”.

During this and the previous meeting we tried to write some probing questions, to focus our assessment. Looking back upon these questions we realize that only a couple of these truly get at the fundamental concepts we are trying to assess, particularly “what if we let the bowling ball continue to swing?” That question challenges students to rectify the concept of conservation of energy with the observation that the ball will eventually stop due to friction.

documents and resources

• summer meeting goals - helping direct us in analyzing our evidence and revising our lesson study
• revised lesson study - including probing questions (note: sheets not in order. . .)

(c) 2009 ronnster/oharanator productions