Numeracy is a fundamental component of the Australian Curriculum as a General Capability in each subject. Here, we report on an aspect of a larger project that aims to provide insight into how teachers can assist their students to develop a critical orientation to life-related situations through a cross-curricular approach to numeracy. Specifically, we draw on data collected via lesson observations and semi-structured teacher interviews exploring the use of mathematics in a critical fashion within the teaching of two subjects outside of mathematics--English and social education. Our investigation revealed that attention to the details of a rich model of numeracy can support the framing of such activities but that time, experience, and initial intent for the learning activity are factors which shape the effectiveness of teachers as designers of such tasks, especially in relation to a critical orientation to numeracy.