You sit down to practice a new scale. It's a tricky one, with some awkward fingerings, maybe a note or two with squirrely intonation, or some other challenge. You figure it out and get it working slowly, then gradually speed it up. By the time you finish, you've played through this thing 100 times and you OWN it! Then, the next day, at your lesson (of course), it's as though you've never seen it before. NOTHING from the previous day's practice session has stuck.
I think it's pretty safe to say we've all been in the above situation once or twice (or 1000 times) in our lives. I certainly have. And if I had a dollar for every time this happened to one of my students, well, I'd probably be in the Bahamas right now.
It's a frustrating situation, and it's entirely preventable. In fact, thanks to about 4 decades' worth of research, we now know exactly how to avoid this unpleasant experience.
Interleaved Practice, also known as Randomized Practice, is a tried and true method of making sure what you do in the practice room sticks. In a nutshell, Interleaving means practicing a bunch of small things mixed up in a more or less random order. Here's a classic example:
Let's say you're working on your melodic minor scales, and they're giving you a ton of trouble. The way most students approach this is to pick one, let's say A-flat as an example, and practice it over and over and over and over until it's becoming easier and easier and it seems like you can't possibly miss even a single note. Then you are done with A-flat for the day, and move on to something else. This feels like progress! But, as often as not, the next day it feels like starting from scratch.
An interleaved approach is a little different. In this method, you pick a few things to work on... maybe the A-flat and C-sharp melodic minor scales, a double-tonguing exercise, an arpeggio exercise, and a short flow study. You practice each one for 2-3 minutes, with the goal of improving some specific aspect. In that short time, you might get a little improvement, but it isn't going to start feeling easy, and you're not going to go super fast. But, you move on to the next thing on the list anyway. You go through the list a few times, so each individual item might get 10-15 full minutes of practicing, just like with the traditional approach, but it's broken up.
Interleaved Practice For the Win!
Practicing this way is harder. Each time you switch from one thing to another you have what is called "Task Switching Cost" - your brain has to struggle to recall what you were doing when you left off. At the end of the session, you're maybe doing a little better, but not as much as you would have if you'd just done it all in one block. BUT, the next day, you pull out your A-flat scale and, shockingly, it's about where it was when you left off yesterday. You're retaining what you learned. After a few days of interleaved practice, you're way ahead of where you were when you started. You can't wait to get to your lesson to show off your skills! And, when you play the scale at your lesson, you NAIL it! Nice!
Why does this work? Well, it seems that the harder the brain has to work to do something, the more likely it is to put that thing into a "more accessible" part of long-term memory for later use. Think of it this way. If you do something over and over again for a while, that task can stay in short-term memory until you're done. Then, after a little while, it gets flushed to make room for more pressing needs, and tomorrow you're right back to square one.
With interleaving, you come back and try again fairly quickly. At this point, some of the task is still floating around in short term memory, but some has likely already been flushed. Your brain has to work hard to do the task all over again. Brains hate having to work hard at the same thing twice, so this time it puts some of the task into longer term memory, just in case.
Then, you come back a third time. Now your brain has more of what it needs to get the job done, but it turns out it still has some missing pieces. It says to itself, "Self, this is clearly an important task, and it looks like I need to remember how to do it. I don't want to have to struggle like this again. I hate struggling. This is going in a prominent place in memory, and I'm putting a sign up so I can remember where I put it next time."
OK, I may have gotten a little carried away anthropomorphizing the internal workings of the brain, but I think it's a fun way to think about what may be happening "under the hood."
Have you ever tried interleaved practice? Tell us about it in the comments!!