I can't pick up the key in the bathroom, and I once picked it up but the door wouldn't unlock?!
After trying again, I found out that you should go to the door, come back for the key and see it. Afterward, you will go to the door and come back for the key again!? weird...
I ran around for 10 minutes and couldn't figure out what to do even though I saw the numbers and ran away from the monster. The game is create in terms of graphics, sound etc but the puzzle is bad, I have to say that.
Pretty good game, I think you've not used the classroom floor to fullest extent. I'm sure it took alot time to draw but the player only stays there for a short while! You could have done some tricks in there to have the player stay in there for longer.