How do I allow a student to change the data for a specific topic?

If you want the enrolled student to be able to add e.g. more detailed assignments and literature to the topic, go to:

The Information system Teacher [course selection] (Topic Lists) Enrol and cancel enrolment of students

for the selected student, click on the "Edit information" option and select the "Enable the student to modify the name, description, literature" flag.

You will be notified by email when the student makes the change.