What started in the Netherlands by the end of 2006 as a 'national centre of expertise for teacher education in arithmetic and mathematics' (abbreviated in Dutch to ELWIeR) now also appears to have strong positive effects on the professional development of the participating educators.

The lecture will present the structure and procedures of ELWIeR, and will then focus on two of its main working areas: updating the didactical resources, and doing applied research in teacher education. The production in both areas should support teacher educators and reinforce their knowledge base. Of either area a specific case will be discussed (a new chapter for a didactical handbook about algebra teaching, and a study on how to improve the professional numeracy of prospective primary teachers). The lecture concludes with an analysis of the effects on professional development.