I think your conception of "being taught" is naive. A sixty minute "course" in anything teaches very little. It tweaks the short term memory and not much else. To really create learning you need to do something to move the skill/information/whatever to long term memory at least. Humans learn by physically changing the brain - redirecting synapses between neurons. But it isn't an instantaneous process. It takes some work and some active learning - practice. This is the purpose of exercises in coursework and the purpose of taking notes in class. Activity and repetition.
If I tell you (once) that the answer to a particular problem is forty-two and then ask you five minutes later, you will likely remember it. Maybe not if I tell you while you are distracted or distract you sufficiently in the interim. But if I ask you a year later you won't know the answer unless you have done something with it in the interim.
This is discussed in the book The Art of Changing the Brain by James E Zull. It is pretty fundamental to learning theory in general.