I have recommended this for years. Have complete audio and a 1 frame/second video in every class and let the kids know it. Keep the tapes for two weeks. With today's digital technology, this could easily be done. They should even make live video and audio from each classroom available on the internet. Why not? We are paying for what they are doing in the classroom. Why shouldn't we be able to randomly check up on what our employees (the teachers) are doing?
Probably go with live video if you trade off on quality.