9.15 a.m. standardized snack within the frame of the regular break, 9.45 a.m. to 12.25 p.m. everyday school life, 12.25 p.m. either lunch (control) or water as a beverage (intervention of 'skipping meal'), 12.45 p.m. to 1.15 p.m. regular lunch break, 1.15 p.m. to 14.10 p.m. regular school lesson. 14.15 p.m. computerized tests of executive cognitive and basal (alertness) functioning, 3 p.m. lunch for the 'skipping meal'-group. Parameters of cognition with relevance to everyday school life are measured by a computerized test program developed by the Institute of Working Learning and Aging (ALA). Usual eating behaviour, sleep behaviour, physical activity and parental education were determined as control variables by questionnaires for children, parents.