The Cognition Intervention Study Dortmund (CogniDo) and the Cognition Intervention Study Dortmund PLUS (CogniDo PLUS) investigated the short-term effects of having school lunch versus skipping it on children's basal (CogniDo) and executive (CogniDo PLUS) cognitive functions in the afternoon. The present Coco study connect this two previous studies and investigates the effect of having school lunch versus skipping it on children's basal and executive cognitive functions later in the afternoon.