Why do the students see courses they do not attend in their timetable?

If the students or their parents complain that their timetable displays courses they do not attend, or that the class register displays two different courses, then the school has probably not selected the students in divided courses properly.

Solution to the problem: In the course settings select the students that should attend the course.
How to check if the right students have been selected the in course settings

Incorrect setting of students can cause chaos in the "My courses" view in the student or parent account:

EduPage will warn the teacher about potential problems with students selected in divided classses with a red warning sign next to the course:
Why is there a red warning sign next to my course icon?

Further instructions for course settings: Courses