Empirical studies have demonstrated that students who are taught in a group of students with higher average achievement benefit in terms of their achievement. However, there is also evidence showing that being surrounded by high-achieving students has a negative effect on students' academic self-concept, also known as the big-fish--little-pond…

Teachers make a difference for the outcome of their students in science classrooms. One focus in this context lies on teachers' professional knowledge. We describe this knowledge according to three domains, namely (1) content knowledge (CK), (2) pedagogical content knowledge (PCK), and (3) curricular knowledge (CuK). We hypothesise a positive…

School motivation and attachment typically decline after the transition to middle school. According to the stage-environment fit approach, extracurricular activities are supposed to promote motivation. However, research has shown that the effects depend on the quality of the activities, which usually is measured by assessing students' individual…