Test your judgement
Knowing the term is one thing. Judging a real screen is another - and it is the part that actually pays. Each check shows you two versions of the same design for a stated goal. Back the one you think works better, then see the answer and the principle it turns on.
You are shown two versions of the same design - a button, a menu, a toolbar - with a clear goal stated underneath. Pick the one you think serves that goal better. The answer is revealed straight away, along with why, and a link to go and read the principle it rests on in the glossary.
Every check turns on a single, defensible principle for a stated purpose, so the "better" answer is genuinely decidable rather than a matter of taste. Some checks have no single winner on purpose - because the most valuable lesson in UX is reading the context, not applying one rule everywhere.
This is the rung above the rest. The glossary is for reading a concept, the flashcards for recalling the term, the quiz for naming it from a definition. This is for looking at a real design and deciding what works - and being shown why. Confused two ideas? The comparisons set them side by side.