Who is allowed to choose the topic and when?
Topics may be chosen by a student registered or enrolled in the course without enrolment problem. A student who is not registered without a problem may be registered individually by the teacher.

If the topic does not have a "student's enrolment in the topic must be approved by its supervisor" setting, the application will register the first candidate in time until the topic capacity is exhausted. Otherwise, using

The Information system Teacher [course selection] (Topic Lists) Enrol and cancel enrolment of students
specify who you are enrolling to the topic.

1 Select the desired student and save the change.

A student cannot enroll out of a topic if the enrolment has already been closed, or if it is a topic for which the teacher has to confirm the enrolment (after confirmation the student will not log out) or a topic for which an action is registered. If the topic has its own login date, this date takes precedence over the schedule setting (see previous question).