Supposedly, the more you know, the less you fear. But there is knowledge that incerases your fear – or at least it should, if you know what is good for you. No, you do not need Cthulhu Mythos to have this effect.
Chalk. Just your usual chalk, holded in fingers by your teacher.
He draws – leave traces on blackboard – with delicate, crushed mix of white bones. Deaths of countless small marine organisms serve to teach children about boring, irrevelant crap.