Some social activities are for free but for others we charge a fee. The fee covers the costs we make to organize the activity. To be sure to participate in a certain activity it's best to book a ticket as soon as possible. Tickets for social activities purchased online can only be paid by credit card. For the free activities, no registration is required.
During the summer tickets can also be bought at the office of the Summer School. Please note that you can only pay by card and not cash.