Randy Gaul has written a nice introduction to hash tables, in part to learn about hash tables.
In the next iteration of the topic maps course, I should have only a topic map (no papers) as the main project. Require draft maps to be posted on a weekly basis.
So that design choices can be made, discussed and debated as the map develop.
So that the students are teaching each other about the domains they have chosen as they are constructing their maps.