One of the strategies I explore in my book is interleaving. I first came across interleaving through the Master's programme from Ambition Institute (side note: if you're looking for an MA, look no further) and, full transparency, went into my classroom and used it completely incorrectly. We know that non-examples are helpful when understanding abstract concepts, so I thought I'd share how my thinking and practice has developed over time.
This is definitely not how to interleave
One of the first papers we were handed out on the masters was Dunlosky's toolbox paper and I was immediately fascinated by interleaving - the experiment discussed in the paper was about properties of 3D-shapes, how could I not be drawn in?! I immediately started thinking about how I could use this in my classroom (first mistake).
So in I strode the next lesson, armed with this new tool in my toolbox and ready to put it to good use. I'd planned my lesson, so pulled up the slides and got to work. I was working on probability trees with year 9, but having covered Pythagoras' theorem a few weeks prior had mixed a few questions to do with that between my slides on probability trees - I'd interleaved! (Spoiler alert: I definitely hadn't). I knew a key part of interleaving was that things had to be mixed up (check) and that it must be effortful, making sure students were having to think hard about what they're doing (from the looks on their faces I was pretty confident I'd nailed this one too).
What happened? Well firstly, a fair number of students had forgotten how to use Pythagoras' theorem, so it took some time to re-teach them. But once that was out of the way we swiftly went back to probability trees, or so I'd hoped...
It quickly became apparent that in the time we'd spent on Pythagoras' theorem, students had forgotten a fair portion of the fresh information I'd given them about probability trees. Meaning I then had to spend the next 10 or so minutes re-doing the examples I'd just taught them before getting them to do some practice themselves. However, still convinced I was on the right track (remember: I'd mixed things up and the students were thinking really hard!) I let them practice some probability questions for a bit then moved on to my pre-prepared slide taking them back to Pythagoras. Whilst there was a bit more success this time around, this is all very relatively speaking as the initial success rate had been so low. It was also a pretty similar story when we switched back to probability trees. Thankfully, for me and my students, I soon learnt that this most definitely wasn't interleaving. At best my students got an opportunity to practice Pythagoras' theorem; at worst they got confused and it hindered their learning of probability trees. The truth is probably somewhere in between, with the bottom line being they likely didn't benefit from this as much as I had initially hoped. At this point, it's perhaps worthwhile explaining why I'm sharing this.
Firstly, to demonstrate that interleaving is an incredibly nuanced and often misunderstood technique. Whilst I've come a long way from randomly mixing up topics in a lesson I would still be cautious about saying I use it correctly every time. Secondly, this type of misunderstanding of interleaving is still fairly common (and perfectly understandable given the previous point). This is also not the only type of misapplication - I've also seen it used to jump from one topic to another within a scheme of work, breaking up proper sequencing; as well as used to crowbar in connections between subjects e.g. mixing in a "maths graph question" because it links to studying graphs in biology.
A journalist once said this about world-class football manager, Carlo Ancelotti: "He knows a truth about top-level football: most players don’t need to be motivated. They need to be calmed down." I think this quote is equally true for teachers - you wouldn't have to look far to find a teacher willing to change something about their practice on Monday morning having found a golden nugget of advice over the weekend, because we want to be the best teachers and get the best outcomes for our students. But in not tempering that enthusiasm, we run the risk of doing the exact opposite. What makes truly great teaching is taking a measured approach, calming down and giving ourselves the space and capacity to look beyond the superficial features of a practice and unpack the mechanisms that make it effective - something we'll be doing in part 2...
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