Standardised curriculum or standardized lesson plans (SLPs) have become an accepted strategy to support and improve instructional practices in schools worldwide. These standardised lesson plans (SLPs) were criticized in the 1970s and 1980s for deskilling the teaching profession and reducing the work of teachers to that of mere technicians. This critique is now returning at a time of growing regulation of teachers' work in many school systems. In this paper, we investigate the potential and limitations of the SLPs which are the main component of the Gauteng Primary Language and Mathematics Strategy (GPLMS), a large-scale multipronged instructional reform established in Gauteng, the most industrialised province of South Africa around Johannesburg and Pretoria. Our interest is to engage with the impact of SLPs on teachers, given the frequent claims that teacher autonomy is seriously eroded and threatened by SLPs. We examine the relationship between autonomy and authority, by drawing on the philosophers Peters and Winch as well as on curriculum theorists Remillard, Morris and Hiebert who have studied standardized curriculum materials and their impact on teachers' work. The paper argues for a deeper analytical understanding of teacher autonomy and offers three conditions that can equip teachers to seize "autonomy opportunities" when working with SLPs: (1) standardised curriculum materials of high quality, sufficiently specified so that correct and incorrect ways of following the content and procedures inscribed in the SLPs and the reasons for them are accessible to all teachers; (2) authority which is considered legitimate, applied in a morally justified manner and managed in an educationally sound way; and (3) appropriate use of professional and personal knowledge, when making decisions and evaluating SLPs' prescriptions in context. In the rest of the paper we evaluate the "autonomy opportunities" provided by the GPLMS standardised lesson plans, by examining whether the three conditions were met.