prevent admin accounts to log on server?

I run a network and a few servers in a school.
The scenario is teacher A manages classroom 1, teacher B runs classroom 2, etc.. I run the network and the servers.
I run server 2003, and my colleagues install a few basic images I’ve set up in RIS.
The only way I’ve found to let them do their job, i.e. to fully manage their classrooms is to put the teachers group a member of the administrators group.

Of course everything worked OK until they started logging on the servers and messing things up.

Can I prevent local and remote access to a server 2003 to members of the administrators group?

Or any other way to keep things under control?