This chapter describes a case study of the role of mathematics in physics textbooks and in associated teacher led lessons. The theoretical framework (Hansson et al. 2015) used in the analysis focuses on relations communicated between three entities: Theoretical models, Mathematics, and Reality. Previously the framework has been used for analysing classroom situations. In this chapter, the framework is further developed and refined, and for the first time used to analyse physics textbooks. The case study described here is a synchronised analysis of a physics textbook and associated classroom communication during teacher led lessons, and contributes with an in-depth description of relations made between Theoretical models, Mathematicsand Reality. With the starting point in this case we discuss future uses of the analysis framework. We also raise questions for further research concerning how physics textbooks support and not support a meaningful physics teaching with respect to the role of mathematics and how relations between Theoretical models, Mathematics, and Reality are communicated.