Núria Planas is Professor of Mathematics Education at the School of Education of Universitat Autònoma de Barcelona in Catalonia, Spain. Her classroom research and developmental work lie within the domain of multilingual mathematics teaching and learning.Candia Morgan is Professor of Mathematics Education at Institute of Education, University College London in England, UK. Her research critically focuses on the nature of mathematical communication within different practices of mathematics and mathematics education.Marcus Schütte is Professor at the Institute of Special Education, Leibniz University Hannover in Germany. His research focuses on language-related forms of mathematical learning processes in the primary school with the main focus on classroom interaction.

• SECTION I Theorising the complexity of language in mathematics teaching and learning 1. Developing a perspective on multiplicity in the study of language in mathematics classrooms 2. Language, paralinguistic phenomena and the (same-old) mathematics register 3. Bewitched by language: Questions on language for mathematics education research 4. Learners’ language in mathematics classrooms: What we know and what we need to know 5. Content and context specificity matter in the ‘how’ of language responsive mathematics teacher professional development 6. Conceptualising and researching mathematics classrooms as sites of communication SECTION II Opening spaces of learning with mathematics classroom research on language 7. The role of mathematical vocabulary in moving from the particular to the general with visual 8. Mathematics through play: The influence of adult intervention on young children’s shifts between play and mathematical discourses 9. Multilingual mathematics learning from a dialogic-translanguaging perspective 10. Quality dimensions for activation and participation in language-responsive mathematics classrooms 11. Real-world contexts in the mathematics classroom and their impact on the pupils’ language and mathematical learning 12. Preservice teachers learning from teaching mathematics in multilingual classrooms