Using mathematical modelling to solve problems appears in all year levels in the Australian Curriculum: Mathematics (v. 9), and is probably the most authentic way of teaching mathematics in context. However, the term mathematical modelling, even if familiar to teachers, may not be well understood or enacted confidently by teachers in their pedagogical approaches. This article explores the mathematical modelling process and provides some examples of how a mathematical modelling approach can be used in Primary mathematics classrooms, including through the use of 3-Act Tasks.