Connecting theories is an activity in the practice of many mathematics education researchers. Broadly speaking the theories—or theoretical perspectives—being connected come from within the field of mathematics education (“home-brewed” theories) or from outside (psychological, sociological, anthropological; philosophical, linguistic etc. theories), and they come from the same discipline or from different disciplines. As a consequence the researcher needs methods and strategies for connecting theories. Prediger et al. (2008) have taken the “first steps towards a conceptual framework” with a terminology—or a meta-language—for dealing with this issue. The terminology, which is based on the work in the Theory Working Group of CERME, presents strategies for connecting theories as pairs of strategies (understanding others/making understandable; contrasting/comparing; coordinating/combining; synthesizing/integrating locally) within a scale of degree of integration from “ignoring other theories” to “unifying globally”.