Currently, Ressu has approximately 450 students and 50 teachers. Two thirds of the students are Finns and the remaining one third consists of some 50 different nationalities. Ressu has as least 40 classrooms.
In Finland, the comprehensive schools provide basic education for primary and lower secondary levels and their tasks include both teaching and a broader educational role. Their objective is to provide each pupil with the opportunity for diverse growth and learning and for development of healthy self-esteem. All comprehensive schools aim to provide good basic skills and knowledge and sufficient all-round learning. Ressu is a public school and is managed by the City of Helsinki.
During World War II, the school building served as a military hospital. the Russian airplanes bombed the school's play ground during the world war II.