This..............this......................makes my entry into the contest have no possible chance whatsoever. ;A;
Seriously though, I'm glad that you were able to get this done before the contest was over. Overall, you definitely portrayed each of the characters in a way that makes them memorable. They don't sound flat, monotone, or inappropriate for the occasion. In fact, the range is well-displayed as well and none of the characters sound the same in terms of mannerisms or voice.
Which leads me to the writing. The writing is exceptionally written and doesn't go overboard with the situation. It's simple, sticks to the theme of the contest with ease, and it exhibits each character with memorable personalities.
Lastly, the mixing feels very authentic, which can be due to some of the sound effects being your own. They're applied thoroughly and don't overpower the voices. I could detect hardly any static in your recordings, so that's a big plus. Also, I'm kinda glad that you didn't put any music into this. It could have offset the ambiance and atmosphere of the school setting.
Overall, I think you really have a good chance of being a top contender for this contest. I wish you the best of luck while I go cry in the corner eating my organic graham crackers and butter.