Typically, when learning a series of topics in Education, we learn the first topic first, then the next, then the next and so on…
However, interleaving theory suggests that when learning a series of topics, randomising the approach to the topics will produce a deeper, more developed understanding of the topics overall.
There is a wide range of educational research done on the topic. In particular, look at the first link below which highlights the improved test scores from students who had been taught using interleaving theory.
This theory is also linked to the idea of spacing, which suggests regular re-visiting to topics can be beneficial to students’ retention. Check out this link for information: http://bit.ly/1otYoaZ .