Items on the calendar that are for a class and can be marked as "complete". Forinstance, a paper, exam, reading assignment, or study session. Grades can be given to assignments.

Categories are used to group assignments for a class, which is useful for both organizational and grading purposes.

If a weight is given to a class's category, weighted grading is enabled for that class. Whether or not categories should be weighted is usually specified in the syllabus give to you by your instructor.

Items on the calendar that can be used for anything. An event is simply time you are setting aside in your schedule to do something, whether it's a concert, class meeting, or a nap. Events cannot be given a grade, nor are they required to be marked as "complete" when done.

A standard file format for transfering calendars between different programs. For instance, you could export your Google Calendar in iCal format and import that schedule into Helium.

A class group is a set of classes within the same academic term, where an "academicterm" is whatever period system your school uses (semester, quarter, trimester, etc.). Groups have astart and an end date (for instance, the beginning and end of a semester). Grades for all classes withinthe group contribute toward the group's overall grade.

Material groups help to better organize your materials. For instance, you might categorize by type of material ("Textbooks", "Supplies", and "Technology"), or you might categorize by class ("Speech 101" and "Sports Medicine").

An item needed for a class or assignment. For instance, textbooks, a laptop, calculate, or notebook.