The phrase "mixed ability classes" should normally be considered to include a surplus. From the moment, that is, that many students are in the same class, it is obvious that they cannot all have the same abilities, the same readiness, and the same personal characteristics. It is a common feeling among general education teachers that what characterizes the student population in their classes are different needs and abilities, different interests, and different learning styles. In mixed ability classes, students with special educational needs coexist with students with different linguistic and/or cultural backgrounds. The academic heterogeneity of the school class - particularly with regard to certain characteristics, such as gender, culture, mother tongue, readiness level, interests, learning style, and students' background experience - is intensified if the special educational needs of gifted students, students with learning difficulties, and students with sensory, intellectual, and/or physical disabilities, who are integrated into mainstream schools, are also taken into account.