The teachers have super vampire sort of powers, instead of draining blood, they drain your will to live, your strength, and then at the end of the lesson they give some back so you can move on to the next lesson. Happy?
Get ready for a bad metaphor - School is like a blender. you are a frige full of vegetables. Depending how much vegetables (effort) you put in the blender will decide on the quality of your salsa. Although you may feel empty inside when you're done, you've created a masterpiece that will get you far in life (until it goes bad!)
Bad things:
Death
Poverty
Homelessness
School
Other stuff
Life
School
Rebirth
Did I mention school?