In 1968 we were told to pick a semester project for wood shop. One of the choices - offered by the school - was a crossbow! My buddy got the kit and finished it but his Mom had to come to school to pick up the arrows. (I know, they're called bolts)
During class we snuck out and tried it with a triangle ruler from drafting class. We learned that, at the proper velocity, a drafting ruler can penetrate the cinderblock wall of the brand new gym!
Now that was when education really taught you something!