How does one actually learn? Do any of you go to college to learn, or to get a degree? What's the difference?

Im sitting in this class that takes tons of work and memorization, its about art history because its one of the requirements, and I can't remember much of what we went over the first three weeks. Are people supposed to be able to remember everything they learn in a class? Is that expectation unreasonable?

How do you make sure to actually learn it all instead of memorize and then forget it a few months later?