This paper describes two courses developed at Universiti Brunei Darussalam for pre‐service and in‐service teachers who are trained to teach science at lower secondary level (ages 12–14). The courses are designed to focus on applying mathematics to solve science‐related problems. The content and coursework exercises aim to integrate mathematical knowledge, skills, problem solving, mathematical reasoning, and mathematical modelling at an elementary level. Details of the contents, sample exercises, students' responses, and modes of teaching and assessment are discussed.