There are several forms in Aeries that can be used to control what classes meet on what days and times.  

The School Options Bell Schedule is the default Bell Schedule.  The Bell Schedule controls the length of each period.

There are two additional forms in Aeries that can be used to further define the School Options Bell Schedule.

One form is the Block Schedule Calendar which is used to define which periods are meeting on each day. For example, a first period class meets one week on Monday, Wednesday and Friday and not at all on Tuesday and Thursday. The following week it meets on Tuesday and Thursday and not at all on Monday, Wednesday and Friday. It continues on this Schedule for the remainder of the year.

The second from is the Bell Scheduler which is used to modify the default Bell Schedule to a Custom Schedule for a particular day.  It defines what time the periods meet.  For example, a Custom Bell Schedule can be setup for testing days or a minimum day.