Interleaving and Grit

Screen Shot 2012-12-28 at 11.07.54 AMI’m intrigued by the idea of interleaving. I know, I know, it looks like a typo. I must have meant “interweaving”… When I first read of interleaving, I was sure that the authors had typed it wrong. It’s a weird word, but a cool, simple concept to incorporate into your teaching.

So what is interleaving? I tried for a while to come up with my own concise definition of it, but I couldn’t do any better than Rohrer and Pashler (2010) did, so I’ll leave it to them:

If multiple kinds of skills must be learned, the opportunities to
practice each skill may be ordered in two very different ways:
blocked by type (e.g., aaabbbccc) or interleaved (e.g., abcbcacab).
Until recently, experimental comparisons of blocked and inter-
leaved practice had been limited to studies of motor skill learn-
ing, where it has been found that interleaving increases learning
(Carson & Wiegand, 1979; Hall, Domingues, & Cavazos, 1994;
Landin, Hebert, & Fairweather, 1993; Shea & Morgan, 1979).

Rohrer and Pashler expand on their mention of “motor skill learning” and discuss how much better it is for a batter to practice against different pitches in different orders, instead of doing a block of fastballs, a block of curveballs, etc. Presumably, interleaving is better for the pitcher as well. Interleaving keeps athletes on their toes and thereby sharpens their skills.

But how could interleaving help learning in the classroom? One easy way to incorporate interleaving is to alter the structure of math and language homework. A lot of practice assignments in math and language rely on blocked drills (e.g., a long series of Spanish words to be translated into English, then a long series of the opposite), but students might benefit from having to face different types of problems as they go (e.g., one English–>Spanish translation, followed by a Spanish–>English one).

Remember homework assignments from your math book when you were a kid? In my math books, I had to do a few problems from section A, a few problems from section B, and a few problems from section C. In each section, the problems were blocked–they were basically the same, addressing the same skill, just with different numbers thrown in. At times I could more or less go on autopilot and perform the same procedure without thinking too hard. When I finished one section and went on to the next, I had to readjust my procedure to the skills being tested in that section. And so on.

If I were interleaving, however, I might have done a problem from section A, followed by one from section B, followed by one from C, then back to B, then to C, then to A. Or something like that, which would keep me on my cognitive toes.

So let’s say I was designing a grammar assignment for my students. I could have them circle the direct objects in a series of five sentences, then move on to circling the subjects in a series of five different sentences. Maybe a third section of five sentences would require them to circle all the indirect objects.

That would be the blocking way of doing things, and that is exactly what I used to do (the grammar book I designed can bear witness to my unthinking tendency to work in blocks). But instead I might do this:

1. Identify the direct object:

The team won the game because of great coaching.

2. Identify the subject:

Somewhere in the forest lurks a big, bad wolf.

3. Identify the indirect object:

The old man told the children a story.

4. Identify the subject:

What do you think?

Studies suggest that interleaving the exercises this way (and the different skills the exercises test) increases student learning. But it isn’t some silver bullet that helps students learn things more easily.

Rohrer and Pashler cite Rohrer and Taylor (2007), a study in which college students were given four different types of math problems to solve. One group did blocks of each type of problem; another group faced the problems in an interleaved format. In the short term, the block-format students outperformed the interleaving students (mean scores of 89% and 60%, respectively). Yikes! What good, then, is interleaving?

Well, on a test given one week later, the interleavers’ average rose a bit and the blocking students’ average plummeted–63% to 20%! It looks as though interleaving helps you really learn something, even if if it makes things harder in the short term.

As you can see from this post’s title, I see a connection between these data and that word grit we hear a lot these days. Interleaving problems makes assignments harder–maybe even a bit more annoying–in the short term, for the sake of a larger payoff and deeper learning in the long term. Would our students see the value in that? Do our students understand that a lower initial score isn’t something to be afraid of, especially if it means they learn it better?

I think a lot of us wonder how we can really encourage grit into our classroom, and I doubt many of us think we can make our homework assignments seriously grit-fostering experiences. But it seems to me that interleaving problems offers one small way to make assignments more difficult, not for difficulty’s sake, but for learning’s sake. Interleaving might send the gritty message that “I know it’s hard now, but stick with it and you’ll really learn this stuff.” It’s certainly worth a try, right?…*

Further reading:
“Everything You Thought You Knew About Learning Is Wrong” by Garth Sundem (Wired)
“The Trouble With Homework” by Annie Murphy Paul (NYT)

Rohrer, D. & Pashler, H. (2010). Recent research on human learning challenges: Conventional instructional strategies. Educational Researcher, 39, 5, 406-412.

Rohrer, D., & Taylor, K. (2007). The shuffling of mathematics practice problems boosts learning. Instructional Science, 35, 481–498.


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