The aim of this three-year study is to further contribute to the understanding of how relations between Reality – Theoretical models – Mathematics are communicated in different kinds of instructional situations (lectures, problem solving and labwork) in Swedish upper-secondary physics. A developed analytical framework from the pilot (Authors, 2015; 2019) is used to focus the analysis of the classroom communication on relations made (by teachers and students) between Reality – Theoretical models – Mathematics. The framework, results from an online survey to Swedish upper-secondary teachers on views of physics, mathematics and physics teaching, and results from classroom studies at upper secondary school during 2018 will be reported and discussed at the conference.