Understanding complexity in the mathematics classroom: in memoriam David Clarke.

It is the intention of this special issue to provide an opportunity for mathematics education researchers from all around the world to offer their complementary accounts and to engage in reflective scholarly exchange regarding research into the complexity of classroom practice. Other major international projects informed by the LPS, and led by Clarke, cohered around a desire to understand, model and ultimately optimise the practices of the mathematics classroom. For most of his career Clarke's research activity centred on capturing the complexity of classroom practice through a programme of international video-based classroom research in more than 20 countries. The work of David Clarke The work of David Clarke profoundly influenced the field of mathematics education. [Extracted from the article]