Dates
Calendar
Class times, exams, and deadlines, in one schedule.

Schedule
Time, kept in one place.
Calendar is for scheduling and for keeping the semester's time in one place. Class times, exams, deadlines, and the other dates that already live in Study and Beadle are gathered here. Calendar does not keep a second list.
Class times
The hours a subject meets are on the calendar. Those times come from the schedule already kept in Study.
Exams
Exam dates that belong to a subject sit with the class times, on the day the exam falls.
Deadlines
A deadline already on a class is on the calendar too, including an assignment due date.
Already in Study and Beadle
Study holds the subject schedule. Beadle holds the dates on a class. Calendar gathers both, including the day attendance was taken.