„The effectiveness of education depends on the amount of time that is available for both teaching and learning. Learning and teaching time can be greatly diminished in schools where children have problems inside or outside the home that interrupt the teaching and learning process.“
Univ.-Prof. Dr. Jaap Dronkers, „Features of Educational Systems as Factors in the Creation of Unequal Educational Outcomes“. In: Dronkers (Hrsg.), „Quality and Inequality of Education“ (2010), S. 307