David,
If the teachers have customized their profiles in the software which they wish to use again, copy and paste these files into a different location before updating their OS. The profiles are saved in: Users/USERNAME/Documents/Activ Software/ActivInspire/My Resources/My Profiles.
If the teachers are running the latest version of ActivInspire (1.7.58968) it will look the same whether they are on Snow Leopard or Mountain Lion. (case# 242357)
Hope this helps!