This study draws on previous empirical research within the fields of opportunity to learn (OTL) and peer effects in education. In a recent study, it was argued that the Frame Factor Theory (FFT) could be applied as a theoretical framework to the issue of peer effects in education. Since the FFT predicts that the class composition measured as students’ prior knowledge and aptitude, will have steering and limiting effects on teachers’ instruction, in turn affecting students’ achievement, it was argued that this could be interpreted as one mechanism generating peer effects. Empirical findings from analysis of TIMSS 2015 data supported the hypothesis. Possibly due to poor construct validity, the previous study couldn’t verify the modus operandi of the mechanisms. The FFT predicts that the steering and limiting effect of class composition will affect timing, pacing, and content covered in instruction. From this perspective, the aim of this article is to initiate a synthesis of the OTL- and FFT-perspectives, where OTL-findings on content coverage are included in an FFT-model predicting peer effects in education.

A synthesized theoretical model is operationalized and tested with Swedish TIMSS 2011 data (n = 3,928) in a multilevel structural equation model. The main FFT-construct in the study is a latent variable of “Limitations on instruction”, derived from items in the TIMSS teacher survey. Also, a variable of coverage of advanced content is derived from TIMSS 19 topics through assessments by Swedish eighth grade teachers in mathematics.

The study revealed that class composition, measured as class-SES, to some extent was related to teachers’ instruction in class, through its limitations on instruction, but it was also related to the content that can be covered in instruction. Results reveal a negative relation between students’ average age of arrival to Sweden on the between-class level and advanced content covered. Through both of these effects, individual students’ achievement in mathematics is affected, indicating the presence of a peer effect. The results from the study thereby support previous findings on the steering and limiting effect of class composition on teachers’ instruction, as well as providing a new theoretical perspective on results from OTL-research. The results indicate that differences in students’ opportunities to learn-measured as content covered-to some extent is related to the steering and limiting effect class composition has upon teachers’ instruction. The results are discussed in both a historical and contemporary context.