Background: A considerable proportion of secondary school students gets additional support from private tutoring lessons. Empirical findings on the effectiveness of private tutoring are inconclusive. The instructional quality of the tutoring lessons might influence their effectiveness. Aims: We analysed (1) whether students privately tutored in…

Prior research has shown that quantity of schooling affects the development of intelligence in childhood and adolescence. However, it is still debated whether other aspects of schooling--such as ability tracking or, more generally, school quality--can also influence intelligence. In this study, the authors analyzed intelligence gains in academic-…