Thank you for the clarification. First, I should say that I am also not a lawyer and, therefore, all of this is sheer speculation on my part, especially when Blackboard has refused to say what its patent covers. My interpretation of the Blackboard patent is that potentially it covers any system with exhibits certain implements certain methods when used for supporting a course. What you call items in your data model is irrelevant. If Elgg is never used in the context of a course by faculty and students, then you probably don't have anything to worry about. However, if Elgg is used by faculty and students as a collaboration tool in the context of course then you might be infringing on their patent. I worked with a similar system where we had communities and user roles. A course was just a type of community and faculty, students fulfilled roles. Just because Elgg does not use certain terms in its data model, doesn't mean that you are off the hook.

But I think we agree on the fundamental point: Blackboard's patent should be invalidated. At the minimum, BB should describe to the rest world what they believe their patent covers.