In this within‐subjects design field experiment children's behaviour in the playground was charted as a function of gender and time in the classroom immediately preceding playtime. Playground behaviour was also related to post‐recess classroom behaviour. Twenty‐three 9‐year‐old children were observed for 14 weeks. Classroom behaviour (i.e., task relevant behaviour on standardised seat work immediately before and after playtime) and playground behaviour (i.e., social and non‐social exercise and sedentary behaviour) were observed. Time in classroom before playtime was manipulated so that there was a shorter and a longer confinement period. Results indicated that children were less attentive to seat work as a function of time and that longer confinement resulted in more exercise for boys and more social sedentary behaviour for girls. Social behaviour at playtime and post‐playtime attention to seat work were significantly related. Results are discussed in terms of N