At our school we work with a curriculum year-class system. Children of about the same age are in each group. The curriculum that is described in the core objectives of primary education is divided into 8 years.
When composing the groups, we make a good division between boys / girls and socio-emotional and cognitive areas. We take into account, where possible, friendships as we experience them in the group. This means that it is not self-evident that a group stays together throughout the primary school time. This applies to all groups.