Going into it thinking that you'll be able to use the outdated equipment you buy later on may not be realistic. Not all lenses work on today's digital SLRs, and if they do, they often won't auto focus and they require an adaptor, etc. You'd need to be clear on that ahead of time so you're not disappointed later. However if you go into it with the idea that this would simply be "supply costs" for this particular class, that would probably be better. Because chances of her using whatever you buy after the class are pretty slim, as film and developing are expensive - and unnecessary, really, when digital, once you invest in equipment, is free.
Personally, I'd rather invest in an entry level dSLR (even if I had to save for a while) and get her out shooting if she shows an interest. You could also enroll her in a community based digital photography class if you want - it doesn't have to be in high school. If she decides down the road she doesn't like either the hobby or the camera, at least the newer camera will still retain much of it's value and you could sell it.
My DS 13 has his own dSLR (my old one) and uses it pretty well. He's never had a formal class (yet) but I've taught him basic principles of exposure and he makes technical use look easy (darn kids, lol). My point being that there is more than one way for a teen to learn photography. You should consider all your options. Investing in a dSLR now may make more sense, but it's up to you to decide what works best for you. I just wanted to give you another perspective.
BTW I've bought most of my lenses on Craigslist with no problems whatsoever, and today's kit lenses are actually good to excellent.
