Dedicated print server.
All networked printers (bar 1 or 2).
Script to allocate printer based on OU.

Staff laptops - little HTA that runs when they logon listing all the printers. Staff can then pick the nearest printer to where they are using their laptops. They then have that printer until they logoff or manually run the HTA again.

Mobile classrooms - as staff but with fewer printer to choose from.