Retrieval cue
A retrieval cue is any hint that helps you pull a memory back out of your head, like a keyword, a question, or an image you tied to the fact when you learned it. Good cues make recall a lot easier.
Your brain doesn't store facts on their own. It links them to other stuff: words, pictures, where you were, even a song. A retrieval cue is one of those links. When you trip over the cue later, it drags the memory up with it. That's why a question on a flashcard can make the answer pop into your head when staring at a blank page does nothing.
The catch is the cue has to be there at test time too. If the only thing that reminds you of a fact is your own highlighter color, that won't help you in the exam room. So build cues you can actually use later: a keyword in the question, a step in a process, a real example. Practice pulling the answer from the cue, not just reading it.
Maria keeps mixing up the cranial nerves in anatomy. She ties each one to a word in a silly sentence, so "On Old Olympus' Towering Top" gives her the first letters. In the exam she recites the sentence, and each word cues the next nerve.