The simplest way to do it with standard 802.11 equipment would be to transmit at high gain on channels 2 or 3, 6 or 7, and 9 or 10. But there's lots of devices

The simplest way to do it with standard 802.11 equipment would be to transmit at high gain on channels 2 or 3, 6 or 7, and 9 or 10. But there's lots of devices that cover that spectrum; it'd be cheaper to rip the transformer and magnetron out of an old microwave oven and energize that in the middle of the classroom. Use a pulse width modulator to step down the power by a few orders of magnitude if you're feeling generous enough to not cook your students. *note: Do not actually do this.