Introduction to the papers of TWG24: Representations in mathematics teaching and learning

TWG24 made its first appearance as a new Thematic Working Group at CERME10, focusing on representations of mathematical concepts or mathematical objects because of their constituting an "integral part of the doing of mathematics" (Presmeg, 2002) and thus an important part of teaching and learning mathematics. Indeed, representation has been a crucial topic in research, for instance, in PME groups, in a special issue of ESM, in a special issue of ZDM, in ICME 13 in 2016. In the group's "Call for papers" the term representations referred to thinking tools for doing mathematics encompassing graphs, tables, diagrams, formulas, symbols, texts, concrete models, and, in a broader sense, even gestures, videos, sounds etc.