Two distinct types of content objects are primarily involved: the assignment description bundle itself, and the assignment submission. Assignment descriptions are typically authored by an instructor, and available to that instructor for future courses or other contexts; they may also be linked to particular curricular goals after the manner of portfolios. Assignment submissions, on the other hand, are typically authored by a learner, and they may be the basis for assessment or stored as a sample of the learner's work. The ambiguity in the English term 'assignment' is not helpful here, since it may be applied to both descriptions ("The assignments are in the syllabus") and submissions ("Some of the assignments were turned in late"), so the term assignment will be reserved for the posed description, and submission will be used to disambiguate the content submitted to satisfy an assignment.
A secondary type of object is the rubric for evaluation. In the simplest case a sweeping point system is used for all assignments, but in principle each assignment may be weighed by its own criteria, and so associating a rubric with (or creating a rubric for) an assignment is a basic (though optional) part of description authoring.
Additional objects and activities may be encountered where the assignment serves as an impetus to some further activity (e.g. a discussion about the assignment), and such cases are complementary to the problem space.