The Knowledge Quartet 2003-23: the application of teacher knowledge to classroom pr ****************************************************************************************** * The Knowledge Quartet 2003-23: the application of teacher knowledge to classroom practic ****************************************************************************************** For more than 20 years, my research with colleagues in and beyond the UK has focused on th knowledge of mathematics teachers. Since 2002 this research ´entered the classroom´, to ob teachers apply what they know in the act of teaching mathematics. The result was a theoret for analysing, discussing and developing mathematics teaching. In 2003 we named this frame Knowledge Quartet (KQ). In this presentation I shall describe how the KQ emerged from obse mathematics teaching, and how in the following years the scope of the KQ has been extended in English elementary classrooms to teaching in secondary schools and universities. An exc development has been the application of the KQ to the teaching of other disciplines, such technology and English. Tim Rowland, University of Cambridge, UK