Have or create a couple of courses. Enrol the administrator as a student in all of them. Go to the dashboard and follow the link on the calendar block to view the month. Add two events, one for each course, and make them on the same day. Click on the link for the day (the number of the day in the month). Notice both events are shown. Filter by one of the courses and confirm only its event is shown. Filter back to 'All courses'. Confirm all events are shown.