Our study aims to provide empirical evidence for and against the valid use of primary school students' ratings of three generic dimensions of teaching quality (classroom management, supportive climate, cognitive activation). We examine whether students discriminate between corresponding dimensions in different subjects, taking into account whether these subjects are taught by the same or different teachers. Using data from the German Trends in International Mathematics and Science Study 2015 assessment of 3,853 fourth graders (M[subscript age] = 8.8 years, 195 classes), we conduct multilevel-multigroup confirmatory factor analysis. The results suggest that students only differentiate between subjects when taught by different teachers. The findings also imply that valid inferences from student assessments may be affected by students' experiences with multiple teachers.