|Dennis, when you wrote about your desire for the words on a list to end up in Sergei's head and not simply as ticked off items, I inferred that you meant they'd need to be recycled.
Scott is right, of course, about the importance of multiple exposures, which reminds me of trying to capture an image on film: if you want to truly explore a subject (lexical bit), you'll need to expose it (memory) from different angles (recycling). Where textbooks tend to give a single snapshot, *you* and Sergei can actually create a motion picture.
Example: Before you come up the stairs next time, what if you ask Sergei to brief you on what it's like making your way into the room? I remember 'narrow', 'on/to the left' and 'door'. Does he remember anything? Could you scaffold as he describes the way up to the room? It doesn't have to be a test, you can just ask what he remembers. Eventually, Sergei might be explaining how to reach the classroom to a friend, family member, etc. *And* some of those words on the list of 1000 are bound to be used in his description, in context, are they not?
Hope that helps.