The German education system is different in many ways from the ones in other countries, but it produces high-performing students. The overwhelming majority of German students attend public schools. But, there are also many private schools. Children aged three to six, may attend kindergarten. After that, school is compulsory for nine or ten years. From grades 1 through 4 children attend elementary school (Grundschule), where the subjects taught are the same for all. Then, after the 4th grade, they are separated according to their academic ability and the wishes of their families, and attend one of three different kinds of schools: Hauptschule, Realschule or Gymnasium. Grundschule teachers recommend their students to a particular school based on such things as academic achievement, self-confidence and ability to work independently.