For all activities you have to sign-up. Some activities are free to join, while for others you have to buy a ticket.
The fee covers the costs of the activity. To be sure to participate in a certain activity it is best to book a ticket as soon as possible. Tickets for social activities can be purchased online and paid for with credit card or iDeal.
During the summer, tickets can also be bought at the office of the Summer School. Please note that you can only pay by card at our office.