Interleaved Curriculums See Huge Improvements in Retention

September 3rd, 2013

In Tampa, a test is underway in eight middle school classrooms to see how effective “interleaved” curriculums are for learning:

Dr. Bjork and others have shown that studying mixed sets of related things — paintings, birds, baseball pitches — greatly improves people’s ability to make quick, accurate distinctions among them, compared with studying as usual, in blocks. Others have found the same improvements when the items being mixed are specific kinds of problems, like calculating volumes, or exponents.

A growing number of cognitive scientists now believe that this cocktail-shaker approach could improve students’ comprehension of a wide array of scientific concepts, whether chemical bonds, parallel evolution, the properties of elementary particles or pre-algebra.

Interleaved curriculums mix questions on related, but distinct, topics. This contrasts with the traditional approach to teaching most of us experienced in school, where students focus exclusively on one concept at a time and repeatedly answer questions about it. This is called “blocked” curriculum.

The Institute of Education Sciences designed the test such that half of each class received “interleaved” homework assignments for two kinds of questions and blocked assignments for another two, while the other half of the class received blocked assignments for the first two kinds of questions and interleaved for the last two.

The test is fairly small, but the results were dramatic: at the end, students were given a surprise cumulative exam of the material covered. Students answered 38 percent of the normal, “blocked” material correctly, and answered 72 percent of the interleaved material correctly.

That small of a test doesn’t confirm interleaving is superior, and certainly doesn’t confirm that it’s superior for all students and all material. But the logic makes sense; by mixing in prior material into homework assignments, students have to go through another step that they don’t have to do while answering blocked questions: they have to identify what the question is asking, and then decide what tool they’ve learned will help them answer it. As a result, they should better understand the material itself, and they should form an association between the tool they’ve learned and the kind of problem it applies to.

In mathematics courses I took, I became very good at learning whatever concept we were focusing on at the moment and applying it to each question by rote. Rather than focus on identifying what the question was asking and figuring out the best way to solve it, I would instead identify the template that each question related to that topic followed, identify each constituent part, and insert them into the concept. Since that was quicker than trying to analyze each question as if it was unique (they nearly always were not), I did whatever would get me to the correct destination the fastest.

In addition, this also resulted in me forgetting material covered toward the beginning of the semester toward the end. I would need to re-learn much of it for final exams. That suggests I wasn’t so much learning the material as learning a mechanical process to follow.

Interleaving is interesting to me because it should help reduce that tendency. Not only will it better force students to interpret what each question is actually asking (and thus better understand whatever topic they learned), but it’s a built-in review of prior material which should reinforce it.