The Grade 2 learner results of the Early Grade Reading Study (EGRS) randomised control trial (RCT) in the North West province showed that the structured pedagogic intervention model that included instructional coaching, lesson plans, and quality learning materials was more cost-effective than a similar intervention model that excluded coaching. These results are read against the growing body of literature that questions the value of RCTs in identifying mechanisms of change. For this reason, two small-scale qualitative case studies were undertaken to identify the difficulty in detecting workings of classroom practice that RCTs cannot show. Three mechanisms of change: the organisation of space, time, and implementation of routines drawn from the work of Foucault, were analysed to interpret observed changes to teacher practice and some of the weaknesses in the EGRS programme.