Abstract
This book contains the proceedings of the twenty-third study led by the International Commission on Mathematical Instruction (ICMI). The study addresses, for the first time, mathematics teaching and learning in primary school (and pre-school as well) for all, taking into account international perspectives including socio-cultural diversity and institutional constraints.
Whole number is the core content area, which is regarded as foundational for later mathematics learning; its teaching and learning are thus very important due to larger impact for later mathematics knowing.