Tuesday, March 13
Day 2 back from break is always the hardest for me. I predicted it yesterday and boy howdy did it come true. Even a cup of coffee with breakfast and another at lunch have not been successful in perking me up. But no matter what I am overjoyed to be back at work. I know I will have more energy tomorrow, and today worked out pretty well.
Physics: Lens lab! We have some light sources in boxes with arrows on them, so the students projected the image on a screen and made some measurements, then moved some stuff around and gook new measurements. It was far easier to focus the image of the filament than it was to focus the image of the arrow. Next year if we do this, we’ll just do that instead of fooling with the arrow. They’ll measure to the middle of the box top instead of the front face of the box. It’s not any harder to do and is far, far clearer and easier to focus. Overall super fun to fool with, although I did have to give students the instructions not to try to wear the lenses as a monocle because the edges are far from smooth after so many years of use.
Honors Physics: Circuits! First we did the wire+battery+bulb activity. I had already set it up for the AP class weeks ago, but I have more honors students than AP students, so I needed more bulbs. I went to go get them in place where bulbs have been for those weeks, and they were gone. I all but tore the classroom apart looking for them everywhere I could possibly think of multiple times. ARGH. I finally asked the dept head if he had any, and he did have a handful down in the basement, which required going outside in the rain to get to the access door. Of course, on the way there I slipped and ever so gracefully and delicately sat down right in the middle of a mud puddle. Whatever. I’ll survive. Gotta get the lab set up. I tried all the bulbs we found in the basement. Not a one of them worked.
Fine! A few students can work in pairs instead of each one having their own set-up. It’s more interesting if they can all have a setup in their hands at once instead of one person playing while the rest watch, but needs must.
Once everyone had gotten a bulb lit up, we used the chirpin’ chick to added “complete loop” to our list of things required for current to flow in a circuit. I mentioned that this is not always the case for things like lightning, but for all the circuits we would be building and measuring it was true. On to the circuits! First, I grabbed the bag of holiday lights to give each group a set. Turns out my box of bulbs was in there. Son of a gun! At least now I know. Anyway, the students learned how to strip wires from holiday lights with scissors because I only have two pair of (broken) wire strippers total instead of two pair per group. Once they’d stripped a few bulbs, they built their first circuit with the holiday lights and realized that it was pretty hard to get all the parts together and keep them working, so I handed out rubber bands to hold stuff on the batteries.
Next step was handing out a sheet of aluminum foil with a couple sticky notes, paper brads, and paper clips for the students to design their own switches. They made some pretty incredible stuff. After that, I drew some circuit diagrams for them to build with different structures and adding in switches at different places.
I’m not yet going the other way, but maybe we’ll do that after they’ve spent more time with the building and measuring. They were all having some trouble with bulbs not coming on with a single battery, and one group decided to connect together three batteries. I encouraged this. Unfortunately, they connected them together in parallel, so they won’t really see any difference. I said nothing about this. Their reaction when the bulb was hilarious, and it led to a really great conversation about what a battery actually does in a circuit and how structure determine function.
And now in series!
I’m super happy about this. They had kinda blown off my request to build the circuits drawn on the board, but I’m not too worried about it. This is just the skill building lab period. Tomorrow we’ll start learning how to take measurements. I ordered a few new multimeters today out of pocket just to have enough nice, identical ones. The ones they have here are old and huge, and having to teach different groups the intricacies of different meters every time groups are switched up and they have to use a new one is a logistical nightmare worth paying $50 to fix for the foreseeable future.
AP Physics: Today we finished reviewing the final exam and began a discussion of how circuits behave with charging capacitors. The first class I tried bouncing off the final exam question (2011Q2) on capacitors, but it did not work so well. The second class I did some qualitative analysis and discussion of simpler circuits, and that went much better. I’ll back track with the first class tomorrow and do some more combinations of capacitors and resistors, but it is just too complicated. Whatever happens tomorrow, Thursday will be our intro to magnets lab, and Friday will either be more capacitors or on to magnetism!