After pre-school, all children transfer to the primary level (provided they are not kept back). Readiness for school is the transfer criterion. The pre-school teacher - possibly with the support of specific specialised centres - and the parents or guardians are involved in the decision-making process. In several cantons, pilot projects are being conducted with regard to reform of the school entry level (Grundstufe and Basisstufe). In these pilot projects, children aged between 4 and 8 attend mixed-age classes; the school entry level can be completed more quickly or more slowly, according to the child's developmental status.