You can apply all the topics you are interested in. Make a separate application for each supervisor. In application, practise writing of general application for a job. Behind the links you can find a template and a TeX template. Some hints for writing an application can be found here.
If you apply more than one topic, you may attach a priority list with your applications.
The application should be given in printed form to Jussi March 30th, at the latest.
In many cases, the exact content will be discussed with the supervisor.
Topics of Educational Technology
Topics of the Color Research Group
List to be updated.