Tamsin Meaney is professor of mathematics education at Bergen University College, having previously been professor at Malmö University. She has worked in teacher education in New Zealand, Australia, Sweden and Norway. Her research interests are varied but centre around the need for mathematics education to support social justice concerns. Whilst in Sweden she started the research group, Young Children's Mathematics. Ola Helenius has a PhD in mathematics but in the last few years has worked in mathematics education at the Swedish National Centre for Mathematics, Gothenburg University, where he is currently deputy director. He is interested in mathematics education at all levels and was part of the group who provided advice for the development of the revised Swedish curriculum for preschools in 2010. He belongs to a number of research groups at different institutions across Sweden and is also part of the Scandinavian research group, Young Children's Mathematics. Maria L. Johansson has a PhD in mathematics and also one in mathematics education. Her PhD in mathematics education focused on issues to do with mathematics in preschool, particularly to do with the professional development of preschool teachers and childcare workers. She is an Associate Professor at Luleå University where she works in teacher education. Her research interests are wide ranging, covering both mathematics and mathematics education for a range of ages. She has also published extensively with the research group, Young Children's Mathematics. Troels Lange has been a mathematics teacher education for twenty years, first in Denmark, then Australia and Sweden. He currently works at Bergen University College in Norway where he is an Associate Professor. His research interests centre on how children experience learning mathematics but he has published on a range of different issues to do with mathematics education. Since 2011, he has been part of and published with the research group Young Children's Mathematics. Anna Wernberg is associate professor in mathematics teacher education in the Faculty of Education and Society at Malmö University. She had previously worked at Kristianstad University and Borås University, also in Sweden. Her research interests focus on the use of learning studies in mathematics classrooms for young children. She has also published extensively with other members of the research group Young Children's Mathematics.