Well, the thing is, CRT-based televisions are not something you want to play with unless you know and understand exactly what you are doing. You can easily -kill- yourself (or instruct your students wrong, and then they -kill- themselves). I am always wary when I have the back off a monitor (and really, any powered circuit - even low voltage ones!). So be careful. However, I doubt that you will be able to teach yourself everything you need to know about television repair inside of a year, to the point where you would have any business teaching others. I am really surprised that they (the school) would allow someone to teach something they aren't qualified to teach (then again, there's the US public school system - but I digress)...