Interleaving involves teaching subject content not in a continuous block, but in chunks which pupils revisit over time. This approach helps embed new learning in long-term memory, through the act of repetition. Repetition for learning is not simply about replicating previous lessons; it involves the act of retrieving previously learnt knowledge and then developing it.
We interleave subjects that involve a lot of interlinked but discrete content. In subjects like science, pupils cover a wide range of subject matter. If this were taught in blocks, irregularly, pupils would be far less likely to remember specific content long-term than if it is embedded through interleaved learning.
We complement interleaving with a process of low-stakes quizzing. Pupils sit a mini-test each time they revisit an area of learning. This facilitates the retrieval of previously learnt knowledge, as well as indicating to teachers and pupils where gaps in learning lie that need filling.
The subjects we interleave are maths, science and PE. See the document below for an example of what interleaving looks like in practice.