If the teacher handles all the mixing of stock solutions there should be few problems with safety.
The only stock solution that needs to be mixed to working dilution should be the developer. In most cases, it's 1:1 developer plus water. A high school student should be able to do that safely. If he can't he doesn't belong in photography. Everything else, stop bath, fixer and hypo clearing agent is usually mixed to working dilution from the start. All the student needs to do is pour out the right amount.
A high school student should understand the rules:
• Follow directions and measure accurately.
• Don't mix things that aren't supposed to be mixed.
• Don't spill.
• If you have an accident, wipe it up.
• No food or drinks in the lab.
• Wash your hands with soap and hot water before you leave the lab.
• Report any accidents or problems to the teacher AT ONCE.
If you feel the need to smooth things over with the administration, tell them that you require all students in the lab to wear chemical resistant, nitrile rubber gloves and safety goggles.
Write up a list of safety rules, print them up in large text and post them on the wall of the lab. On the first day of lab, give the students a safety lecture. Tell them that you will give one warning and, if they don't obey, they are out. This kind of "laying down the law" is often what many school administrators want to hear. If you take a proactive approach they will feel better.
XTOL is probably a good developer to use. You can tell the admins. that it is "basically made from vitamin-C." You can tell them that stop bath is "basically the same as vinegar." In either case, you're not lying. Ascorbic acid IS vitamin-C and acetic acid IS the main component of vinegar. You are just explaining things in terms that people can understand more easily.
Provided your students operate in a safe manner, the only thing that could cause you trouble is one of the students having an allergic reaction. This is pretty rare. Millions of people have used photographic chemistry, over the years, and allergic reactions are practically unheard of. In those rare cases where it does happen, wearing gloves, goggles and aprons is usually enough to solve the problem.
As others have said, the dangers of photographic chemistry are quite overblown. Those stories that people tell are usually second and third hand accounts of things that either didn't really happen or that happened years and years ago.
Modern photographic chemistry is quite safe, compared to the way things were years ago. If people behave responsibly I don't think there is any real danger.
