Teaching by telling and teaching for the sake of examination may lead to students experiencing misconceptions in their mathematics lessons. The present study explored how the topic ‘solving simultaneous linear equations’ were taught to two groups of Year 9 students in two government secondary schools in Brunei Darussalam, and the misconceptions that these students have experienced. The instruments used for this study were pen-and paper test items, the ‘Learning solving simultaneous questionnaire’ and interviews. A total of four teachers and 41 Year 9 students participated in the study. Results from the qualitative analyses revealed that teaching by telling still exists in some of the teachers’ instructions and that students lack the conceptual understanding of the procedures. Another qualitative finding is that students’ incompetency in their pre-requisite knowledge of addition and subtraction of integers also deterred them from solving the simultaneous linear equations successfully. Formative assessment and a learner-centred approach are recommended to minimise such misconceptions.