Altogether 38 girls and 46 boys aged four to five years were studied to analyse the linear and non-linear development of fundamental motor skills. The children were grouped into one experimental and one control group to study the effects of an eight-month preschool physical education curriculum. In the course of one year, the balance skills of the girls, the running speed of the boys and the standing broad-jump and manipulative skills of both genders progressed linearly according to the children's age. Two weekly 45-minute physical education lessons instructed by preschool teachers promoted the linear development of the girls' standing broad-jump and non-linear development of the boys' running speed during spring, compared to the group that did not follow a specific structured programme. We encourage educators to organise skill-specific practise and to ensure that the choice of tasks, equipment and environment interact to promote motor development. (Contains 1 table.)