The rapid moving water in your dream represents turbulence in your waking life, and the tidal wave represents a bunch of that turbulence hitting you at once. Now that you've felt that turbulence in force, you can identify it and learn what, in your waking life has you feeling so emotionally disturbed so greatly and suddenly. Perhaps an event in your life has triggered a "tidal wave" of emotion within you?

Also the school and being a teacher seeking a wayward student are both representations of knowledge, power and how both are feeling like they are slipping away in the surging tidal wave of turbulent emotions.

Here is the website I use for dream interpretations, which may help you to further understand your dream. It's pretty good IMHO. http://www.dreammoods.com/