I came across the idea of mixed up practice in Benedict Carey's book, How We Learn, in a chapter on the benefits of interleaving, particularly for learning Maths.
For instance, in "blocked practice", students might work on Maths problems in order, e.g. Problem A, then Problem B etc. following a pattern like AABBCCDD. In mixed up or "interleaved practice", the order of problems is varied, forming the pattern ADCBCDBA.
Carey also cites several studies showing how interleaved practice outperforms blocked practice in skills outside Maths, from badminton to piano playing. These insights are fascinating, as he says "the science suggests that interleaving is, essentially, about preparing the brain for the unexpected."
However, many psychological experiments seem artificial and contrived so I was happy to find a 2015 article in Scientific American that went a bit further:
"Over the past four decades, a small but growing body of research has found that interleaving often outperforms blocking for a variety of subjects, including sports and category learning. Yet there have been almost no studies of the technique in uncontrived, real world settings—until recently."
They mention one study in particular:
"The three-month study involved teaching 7th graders slope and graph problems. Weekly lessons, given by teachers, were largely unchanged from standard practice. Weekly homework worksheets, however, featured an interleaved or blocked design. When interleaved, both old and new problems of different types were mixed together. Of the nine participating classes, five used interleaving for slope problems and blocking for graph problems; the reverse occurred in the remaining four. Five days after the last lesson, each class held a review session for all students. A surprise final test occurred one day or one month later. The result? When the test was one day later, scores were 25 percent better for problems trained with interleaving; at one month later, the interleaving advantage grew to 76 percent."
That's a big difference.
I have two questions:
How widely is interleaving used in your classrooms whether primary, secondary or college/university?
More broadly, do you know of any studies where interleaving has been rigorously tested in more real world settings?