There are things that can help us recall particular Information and they are referred to as retrieval cues.
By using retrieval cues we are able to retrieve memories preserved in our long term memory and bring them to the current situation. Retrieval cues make it easy for us to recall Information we may have rather forgotten. It can be a familiar song,smell or taste that reminds us of what we already know. These are external cues. They can also be internal such certain feelings that may take you back to a memory when you experienced those feelings .
Some questions may give a clue to what you already know so as he scans through the questions he may pick up a word that may bring back a memory of what he has learnt earlier.