You have to be joking! This is a wind-up!
What sort of hair dryers, the hand held one you wave about at your head or the ones which cover your head as you sit in a chair?
On to this you are going to cobble some kind of control system to start and stop the thing when hands are put near it.
And to top it all, these things will be in a school bathroom, near to water.
Have the idiots who told you to do this ever heard of safety?
OK, I know the RSA has a way to go to catch up with the rest of the "western world" but this? You cannot be serious!
JimB
On edit:
I just noticed:
What do they use to operate the control rods in the core, electric window winders out of old cars?