Science disciplines utilize a wide range of semiotic resources such as graphs, diagrams, language, mathematics, hands-on work with laboratory equipment, gesture, etc. (Kress et al. 2001). Here, transduction (that is movement between semiotic systems) has been put forward as a powerful teaching and learning tool because this movement between representational systems brings different aspects of a disciplinary concept into focus (Volkwyn et al., 2019). By the same token, transformation (that is making changes within the same semiotic system) has been viewed as less important educationally. In this presentation, we discuss what we call purposeful transformation, where rearrangement of an equation fills an important function. One interesting aspect of purposeful transformation is that it simultaneously raises both the disciplinary and pedagogical affordance of the equation (Airey, 2015; Airey & Linder, 2017). Similar transformations have been documented in other semiotic systems such as graphs (Rodriguez et al., 2020).