Peruskoulu required that teachers, who had previously worked in very different schools, had to now all work in the same type of school with students with diverse abilities. This meant that teachers needed new instructional methods, they needed to design learning environments that enable differentiated learning for different pupils, and they needed to perceive teaching as a top profession. These expectations led to a wide-scale teacher education reform in 1979 that emphasised Ihe professional development and research-based learning that have been the key drivers of Finland's rapid educational improvement.