Informal Proceedings of the British Society for Research into Learning Mathematics (BSRLM) Volume 30 Number 2, June 2010 Proceedings of the Day Conference held at the University of Nottingham on 19 th June 2010 and the New Researchers’ Day held at the University of Leicester on 18 th June 2010 Using video for professional development: a case study of effective practice in one secondary mathematics department in the UK 1 Alf Coles University of Bristol, Graduate School of Education The use of video recordings of lessons for teacher professional development is under- researched (Hall and Wright 2007, 9). There have been conflicting recommendations related to viewing videos of similar or different contexts (e.g., Hall and Wright 2007, 11 and, Clarke and Hollingsworth 2000, 40). It has been reported that it can be hard or take time to establish norms for discussion of video (Van E’s and Sherin 2008, Jaworski 1990). This paper reports on evidence from the use of video recordings in one secondary school, where teachers commented on finding video watching in a group more useful than lesson observation, with no evidence of this taking time to develop. I report on the practice of using video in this school, which drew on Jaworski (1990), finally offering speculations based on Rosch (1999) as to why it is effective. Long term impact of mental calculation sessions on primary PGCE students 7 Sue Davis University of Leicester In the summer of 2008, I worked with a small group of primary PGCE students and discovered that a brief taught session on mental calculation strategies had a significant impact on their final teaching placement (Davis 2009). In order to evaluate whether there was any longer term impact, I have revisited some of those students who are now approaching the end of their second year of teaching. These initial findings of this ongoing research show that all of these teachers have taught a significant amount of mental calculation methods, and all have a strong belief in the importance of discussion of children’s strategies. A study of the effectiveness of a Dynamic Geometry Program to support the learning of geometrical concepts of 2D shapes 12 Sue Forsythe School of Education, University of Leicester, skf6@le.ac.uk The study described in this paper aims to investigate 12-13 year old students’ geometrical reasoning in a Dynamic Geometry environment in order to answer the question: “In what ways do the affordances of Dynamic Geometry Software act to mediate the learning of geometrical concepts of 2 dimensional shapes?” Two theories which shed light on how humans conceptualise geometric figures and how this sometimes leads to misconceptions will be described. Dynamic Geometry Software may hold some of the answers to the problems students have with conceptualising shapes in geometry, and support the development of geometrical reasoning and the correct use of mathematical language. The importance of designing a task which is