Well, I am disappointed. Somehow I managed to delete a video file of me presenting the concept of kinetic and potential energy (and their relation to mechanical energy) to the S section. It was 13 minutes of amazing teaching, but now it is deleted and no longer exists. I can only guess that somehow I failed to save it, but I don't know.
We continue to study energy--today I talked about Einstein's theory of relativity with the O section. Here is a video clip on time dilation:
Here is a link to a fun interactive twin paradox activity. Very mind boggling, but proven true (mostly).
http://www.pbs.org/wgbh/nova/einstein/hotsciencetwin/
