The timing of what occurs in the classroom can affect how successfully new concepts are learned. This paper analyses two promising ways of modifying the schedule of tasks or examples -- the spacing effect and interleaving. The spacing effect refers to improvements in long-term retention if practice sessions are separated by delays. Interleaving refers to the benefits of mixing different types of examples or problems within a series, such that contrasting items appear side by side or consecutively. These techniques are supported by a body of evidence which suggests that they can boost the durability and transferability of learning, and both are straightforward to implement given that they only require manipulating the schedule of learning experiences. However, research into metacognition suggests that classroom adoption of the techniques is likely to be undermined by persistent misconceptions about how learning and memory work, and that while teacher engagement with research evidence could help to promote the techniques, their use is context-specific. As discussed in the paper, this issue implies a need for focused and contextualised professional learning, which could be enhanced via the application of the same techniques to the professional learning activities carried out by new and in-service teachers.