How to use "class" in a sentence

From questions of this class spring all our constitutional controversies, and we divide upon them into majorities and minorities

"His last class was yesterday at four

They say he finished class at five and left as normal."

He remembers hitting that idiot of a boy Harris because he made a mistake in the geometry class

Left-wingers and right-wingers differed about certain details, of course, but their only major point of contention centered on the identity of those who would be permitted to be a part of the privileged ruling class, once the power had been sufficiently centralized.

There were people of every class and profession, but they were all dusty; their skins were dry, their lips black and cracked, and all of them looked very afraid.