Judith MillsThe Numeracy Development Project has been systematically introduced into New Zealand schools since its conception in 2001. For many teachers, successful implementation of this mathematics education reform required a transformation of long held beliefs and practices. This shift involved moving from a view of mathematics learning as individualistic and passive, towards one in which students come to do and understand mathematics through participating in collaborative activity. This change in pedagogy and the required content knowledge has brought a range of challenges for many teachers. The purpose of this short presentation is to share the journey of two lead teachers (coaches) working with a mentor to enhance their understanding of number in the mathematics classroom. The mentor was a school adviser and the coaches came from schools that had previously been involved in the Numeracy Development Project. The process took place over six months and was aimed at improving both pedagogy and content knowledge of the in-school coaches and other teachers within their schools. A particular emphasis was placed on improving student learning in multiplicative and proportional thinking.