The rhetoric around STEM education has involved an increasing number of curriculum reports and research studies encouraging secondary teachers to connect mathematics and other STEM disciplines to showcase its usefulness and purpose, thereby enhancing students’ engagement and achievement in mathematics. Currently, curriculum documents are discipline-specific and most schools teach STEM subjects in isolation. Guided by the Eccles et al. (1983) expectancy-value theory, this study investigated the student and teacher experience through targeted interviews when one secondary school began to connect mathematics and science in Semester 1 of Year 7, 2019. Students had the same teacher for both subjects and for 3-4 weeks in each term, teachers made content connections between mathematics and science through project-based learning (PBL). Semi-structured interviews were conducted with all seven teachers after each project to gain insight into their experience in making content connections and their beliefs about the impact of the approach on student engagement and achievement in both mathematics and science. Eight students were selected for interviews based on their pre-intervention achievement in the Progressive Achievement Test in Mathematics (PATMaths), and level of intrinsic value for mathematics from a baseline questionnaire completed by all students. Intrinsic value was chosen as it is of particular importance to students’ engagement and participation in mathematics. Two boys and two girls came from each of four categories: low achievement/low intrinsic value, low achievement/high intrinsic value, high achievement/low intrinsic value, and high achievement/high intrinsic value. A minimum of one student was selected from each class. Student interviews aimed to understand their beliefs about mathematics and science, to analyse the content they believed their projects demonstrated, and to examine their views about connecting mathematics and science disciplines. Preliminary findings highlight that low-achieving students exhibited a simplistic view of mathematics as calculations and operations, impacting on their ability to identify and use new mathematics content in their PBL projects. While most girls (N=3) preferred learning mathematics through PBL methods, most boys (N=3) indicated preference to learn in a traditional classroom where the teacher presented information. Teachers’ responses indicated that while they believed PBL effectively showcased the usefulness of mathematics, they held concerns about its benefits for student learning. Three key themes emerged for teachers as requisite to the success of the project: teachers’ beliefs about mathematics, their skills in making explicit connections between both disciplines, and level of content knowledge in mathematics and science.