What's the school's budget?
What's the teacher's curriculum? (For example, does he want to demonstrate more than "one light/one reflector" basic lighting? Or, does he perhaps want a couple more lights to show the effects of a fill-from-the-front or a background light?)
Is the school more concerned with buying the best equipment for the money, or demonstrating & teaching basic principles and use? (not a commentary, but a sincere question)
Will the cameras be digital or film?
If digital, why the absolute contraint for flash?
In my opinion, continuous light is better for teaching purposes anyway (whether with digital or film cameras), as well as being cheaper and therefore easier to replace once the inevitable damage occurs under student use (sorry, but I've worked in a school photography department . . . I've got my prejudices!)
Plus, with non-flash lighting, the teacher has a great opportunity to demonstrate color problems and show how to correct them. Lastly, this type of lighting falls squarely within your parameter of "beginner" !