The present study, a result of the pilot investigation "Whole or Half?" conducted by the University of Rostock, raises new questions about the state of research in the area of "full-day schools" and examines the developmental and socialization processes during elementary school age from the child's perspective. Can institutional afternoon care (full-day school or after-school care) have lasting positive effects on children's educational success? The children involved in the project did not benefit from their after-school care attendance. The conclusion of the study is that unless there is a redefinition of education in the afternoon and a reorganization of educational institutions, the "old" institutions will not be able to address the new challenges and thus will not be able to decouple children's educational success from the educational status of their families. The authors propose to consolidate all research into an interdisciplinary "Theory of Full-Day Education.".