Finland's educational system includes pre-school starting at age 5-6, compulsory comprehensive school from ages 7-16, followed by high school or vocational school. Universities and colleges are publicly funded. Classes 1-6 have one main teacher who teaches most subjects, while classes 7-9 have different subject teachers. The 300-student Laajalahden school has 15 class teachers, 5 subject or special education teachers, and other support staff. Common reasons for Finland's success in PISA include high-quality teacher education and training, a flexible curriculum, equal quality of teaching everywhere, support for weaker students, and strong family support.