With the introduction of any new initiative into the mathematics classroom, there is often an assumption that it will produce visible and measurable effects in teaching approaches and pupil progress. Yet, there is a body of research that tempers such optimism, drawing attention to a series of mitigating factors, for example, the deep-seated nature of teachers' practices, their implicit or stated beliefs and values, and their lack of detailed awareness of how they perform in the classroom. Rather than make associative links between these factors and the success of the initiative, our intention is to examine the ways in which teachers are trying to interpret what the new scheme requires of them and how in turn, engaging with it causes them to re-describe both their pedagogic understanding and classroom practices relationally to earlier approaches. Employing data from a small project, we seek to examine four teachers' moves to grapple with this attempted shift from one teaching paradigm to another by considering how certain key terms serve to anchor the teachers' conceptions of themselves during this transition and find that their responses can be idiosyncratic and varied depending on the approaches in which they have been previously embedded. By using theoretical ideas from some neo-Marxist writers we examine these discursive shifts and their relevance to conceiving curriculum change. We suggest that the individual's teaching practice develops as a result of it being understood and enacted through a succession of ideological filters, each adding to the cumulative experience of the teacher.