- Absolute mastery of the core concepts and relationships with class discussions
- Familiarity with course concepts
- Recognition that the lecture sounds like something mentioned in class before
- Recognition of some of the words used in class
- Assumption that some of the words used in lecture are probably on Wikipedia somewhere
But this isn't just about students- it's everybody. Back in the day when I've had to screen technical resumes, you wonder which one of the above applied- did they understand a technology, just play around with it, or just read some blurb about it. Worst case- did they just throw down a TLA that they read about online?
Does "absolute mastery" happen if you ace all the tests in school and get an A for that course? The real world applies plenty of tests on its own- being an "expert" supposedly takes 10 years and means absorbing 50,000 "ideas", though it would be almost impossible to discretely list them all, much less share them with others.
And, expert or not, there's a heck of a lot more than 50,000 ideas in any domain to absorb- so "expert" is in a narrow context. Which goes back to the main point: what do we really know?