The high school system in Finland differs a bit from Scandinavian and Nordic school systems. In Finland students choose the pace of their studies, meaning that they can finish high school in two years if they want or four years if they feel like they want to take it a bit slower. As such, the school calendar differs depending on your choice of pace. The school year generally begins in the middle of August, finishing at the beginning of June. There are no requirements for school uniforms in Finland, with students wearing what they feel comfortable in.
High Schools in Finland give students a lot of freedom in comparison to other countries with the relationship between students and teachers usually very open and relaxed. With this freedom, comes a lot of responsibility for the students to finish their work on time without strict supervision.
Your local coordinator will handle everything with regards to ensuring you a place at your school, but it is up to you as an exchange student to choose your own courses and subjects. Foreign exchange students in Finland usually have a lot of freedom when it comes to choosing their courses with the subject generally chosen being English, Maths or Physical Education.