read a story in BestFriends about the hairworm that starts out in a grasshopper or cricket eating away inside but must end it's lifespan in water so releases some kind of trigger that causes the grasshopper or cricket to take a suicidal leap into water..that was scary stuff to me! and true!
I like the ouija board idea You can take that so many different places I remember playing with one when I was a kid and some wierd stuff happened so just imagine what your mind could come up with
MAYBE they could be playing with the ouija board and contact an evil spirit and they get trapped in the school (somehow lol) and that's where the spirit terrorizes them
I started writing a story when I was about your age about a girl that was in a love with a boy. The boy had a girlfriend that died in a tragic accident and when the "new" girl started to get close to him the spirit of the dead g/f started taking over her body and slowly she began to look like the old girlfriend and act like the old girlfriend ......
but my computer went kaput so I lost the story thus never finished it