Might one of the alternative processes fit the bill? I suppose she could perform the exposure outside class (and document the process with pics) and then develop in-class. I was thinking maybe cyanotype, but I have no experience with alt. processing.
I'm involved in scientific education in a couple of different ways - I've been a graduate teaching assistant for first year university student laboratories for the last three years (biology & biochemistry), and I've judged kids' science fair projects. The focus in both of these roles has been on teaching the scientific method or the philosophy of science - ie, coming up with a falsifiable hypothesis, designing an appropriate experiment to test it, and using a reasonable number of replicates to get some kind of statistics (at the high school level this could be simply taking an average or showing that something happened 5 times out of 6). That, and designing / using controls (not so much at the grade school level, but definitely first year university).
So, depending on the structure of your high school's science program, you might want to consider using this kind of approach. It could be something lame like "I hypothesize that increasing exposure to light will cause more of the photochemical reaction to occur, resulting in a darker print." You could nuance it with controls of some kind or whatever.
The only major requirement is a write-up on the chemical principles employed (and presented as a powerpoint) AND an in-class demo.
Cyanotype is very simple (coat, exposure, wash in water), but the exposure times can be a little long depending on the negative and light source. If you have a reasonably thin negative and a UV box really close to the contact printing frame (or can go outside in bright sunlight) you might get a 10 or even 5 minute exposure, but my cyanotypes are usually 15+ minutes.
Van dyke is a bit faster; 3 to 5 minutes, maybe a bit longer for some negs. I've also found it harder to deal with (it seems more sensitive to paper choice, exposure, coating technique, and processing, than cyanotype). In some respects that might make it better for a science project if you want to get a bit elaborate and do some kind of experimental design.
I actually haven't been able to find too much detail on the chemistry involved (I haven't looked too carefully either), but I'm sure the information is available.