Go in as a demoman and setup sticky bombs at the entrance. Call in a heavy, backed up door a scout and soldier, and wait on different sides of the area. PM the sniper to take out the teacher, while u and other units go in to flank the teacher and capture the control point.
The enemy team will probably send out people, so it's a good idea to have a couple engineers setup some sentry guns while you're at it. Another good thing would be to always have a medic nearby.
