You can create task calendars (as it sounds like you may have) to restrict the scheduling of the tasks to their respective days. By assigning the task calendars, the task will be scheduled only for those days. To assign the task calendar, show the Task Information (right click) and set the Task Calendar on the advanced tab.

However, the display of non-working time (default gray shade) is set for the entire Gantt chart - you cannot show only Tuesday/Wednesday on Course 5 and Thursday/Friday on Course 6.

I personally would turn off the display of non-working time as your definition is variable.