. Teachers were made aware that the aim of our project was to nvestigate teachers' reasoning capacity, their knowledge of reasoning and its relationship to learning mathematics and other mathematics proficiencies, their approach to teachin reasoning, and how their knowledge develops through participation in a program of demonstration lessons conducted by the research team. Semi-structured interview were conducted with individual teachers in the week prior to the teachers observing the first demonstration lesson. The interview focused on their ideas about various aspects of their teaching practice and their knowledge, interpretation and implementation of reasoning in the previous Victorian curricula and in the new Australian curriculum for mathematics The interviews were audio-taped and transcribed. Analysis of the data was undertaken employing NVivo, a computer software program which enables answers from each teacher to be grouped under specific codes. Emergent themes from this analysis were grouped together for discussion. The findings from this initial teacher interview are reported in this paper. Pseudonyms are used to differentiate teachers