# Day 120: Kirchoff’s Laws & Rock vs. Minerals

AP Physics: Kirchoff’s Laws & Plickers

I split the class period today into two halves. In the first half, we got out resistors and power supplies to do the real-world version of the Kirchoff’s Laws lab students did on Wednesday. My directions were to see if the patterns they’d found Wednesday worked with today’s materials. I used the same slide as last year, but students had a much harder time figuring out what to do this year. I think the problem is we spent yesterday whiteboarding a different lab, while last year I kept the simulation and real-world versions of Kirchoff’s Rules back-to-back. Next year, I think I will take advantage of my department’s iPads and the HTML5 version of the sim to do it in my classroom. Then I can split up the labs by series and parallel, rather than by simulation and real-world and working around when I can get a computer lab.

The other half of the class, we used Plickers to revisit some multiple choice problems from last tri’s final exam. One problem asked why the speed of a projectile does not change at the highest point. After talking to some other teachers, I really like thinking about that one from an energy perspective, using the idea that a force perpendicular to the motion will not change the energy. To drive that home, I used a mallet to get a bowling ball going in a circle so we could talk about whether the force from the mallet changed the bowling ball’s energy.

Earth Science: Rocks vs. Minerals

Students used their work from yesterday to identify some of the key differences between rocks and minerals. Since the book of stereograms students used yesterday also had a gem section, I included those in our discussion. Students pretty quickly recognized they had trouble identifying characteristics distinguished minerals and gemstones, which lead nicely into the idea that gems are just particularly valuable minerals.