This might seem a bit boring exercise, but have you ever seen a course registration system with a newsfeed, where you can see in which courses your friends have planned to attend and "like" that? All students are also very familiar with it, so we should have a clear vision of required features. Main new ideas (for the next 6 weeks):

Student should be able to register for multiple exercise groups Students should be able to pre-register themselves in advance. o This helps the department to get enough instructors for the courses.
Student should be able to queue for a specific group (and system should auto-register people from queue if places become available) o This gives good feedback for planning the times for exercise groups
It should be possible to overbook a group It should be possible to create a user account without an account from University of Helsinki (guests) Student should see in which group their friends are registered in. System should be localized in different languages (Swedish, English, Finnish) and languages and translations should be modified from some kind of administrative UI. Generic help texts should be editable from administrative UI. (Lightweight CMS) Student should be able to upload a profile picture System should have a "planner view" where a student should see all possible times for courses It should be possible to change a group in a "transaction" It should be possible to generate PDF reports from course participants and such.