1: The study of mathematics.
2: A word to describe something that is useful in part, but most of it is worthless
3: A word to describe something that takes all your brain power to comprehend.
4: A boring period of time
1: I study mathematics.
2: That doorstop notebook I bought is math.
3: Did you see how Jane's boobies jiggled?! It's like math!
4: Nine o'clock to ten o'clock is math.
The world 'school' can be used to describe an important place that includes (but is not limited to) learning and may contain lots of books, (not to be confused with a library) but you don't care what happens in/to it.
Matt: "Hey, Joe"
Joe: "Hey, Matt"
Matt: "Did you hear about the White House being painted black?"
Joe: "Nah, the White House is school to me."