theatre sound reinforcement
Although schools (and amateur theatres for that matter) often use quite sophisticated lighting rigs and plots, their sound systems usually remain somewhere in the dark ages, with the odd microphone or two run through a simple amplifier driving a couple of fairly basic speakers. Feedback squeals are not uncommon and the only quality that the finished result has is loudness.
The techniques of Sound Reinforcement which the professional theatre has developed over the last twenty or so years have been largely ignored by schools, partially because of the expense of the equipment involved and partially because of ignorance.