Teaching senior secondary mathematics presents a number of challenges, such as provision of a prescribed curriculum, homework expectations and preparing students for externally imposed high-stakes assessment tasks. In order to address these challenges, an increasing number of senior secondary mathematics teachers are incorporating a flipped classroom approach into their teaching. While enactments of the approach vary, it typically involves delegating the more routine instructional mathematical content as homework videos, allowing for more targeted in-class teaching. Traditionally in the domain of tertiary teaching, it is becoming more common in secondary school settings and seems to address students' needs for competence, autonomy and relatedness, which comprise self-determination theory (SDT). This paper looks at a case study undertaken with an Australian grade 12 class where the teacher utilised a flipped classroom approach to teach mathematics 2. Data were collected through an online survey, interviews and classroom observations. The results showed that SDT was an appropriate lens to analyse participants' experiences of the approach, with the teacher being a particularly strong influence on students' motivation for engaging with the approach. The study adds to the limited literature on examining enactments of the flipped classroom in senior secondary mathematics contexts and has implications for practice in terms of identifying the practices and factors which influence students' motivations for engaging in mathematics classes.