How to use interleaving

Why this matters

A seventh grader can get every problem right on a proportions worksheet, because every problem on that page is a proportion. On a mixed unit test, the same student sees two amounts and sets up a proportion for a percent problem, or sees a circle and reaches for pi. The student practiced the steps but never practiced choosing them, and the teacher has to wait for the test to find out.

What interleaving is, and how it helps students choose a method

Interleaving is mixing different kinds of problems in one practice set instead of practicing one kind at a time, which is called blocked practice. The University of Arizona's Learning to Learn guide says interleaving "has been shown to be more effective than blocked practice for developing the skills of categorization and problem solving" (University of Arizona). Doug Rohrer and his colleagues at the University of South Florida point out that in a blocked assignment, "students know which strategy is needed to solve each problem before they read the problem." In their study, 126 seventh graders did the same practice problems for three months, some blocked and some interleaved. On a surprise test 30 days after the review, they scored 74% on the problems they had practiced interleaved and 42% on the ones they had practiced in blocks (Rohrer, Dedrick and Stershic, Journal of Educational Psychology, 2015).

1. Mix problem types students have already learned, in shuffled order
2. Ask students to name the problem type before they solve
3. Send a wrong pick back to what the question asks for and its units

In the Flint activity, Sparky makes each student a five-slide review deck in their chat, about something the student likes, with a different problem type on each slide and a trick slide at the end. Unlike a worksheet, Sparky reads the method each student picks and asks about the part of the question they missed, without naming the right type.

Sparky gets Rafael to spot the trick slide himself

Rafael starts out picking a method from the numbers on the slide and ends up choosing it from what the question asks for. Every student gets the same four problem types and guidelines, and Sparky writes each student's slides and replies from what that student says.

Sparky builds the slides from Rafael's interestSparky sends Rafael back to what the question asks forA right answer gets a harder slide that looks like one type but is another

R

Rafael

Interest: Cooking with his grandmotherStarting point: Solves each type on its own worksheet, picks the wrong method on a mixed test

Sparky

Your slide deck, Mixed Review: Rafael's Kitchen, is ready! All 5 problems are cooking-themed, and none of them say what type they are. Before you solve each one, tell me what type of problem it is and why.

Rafael

proportion bc theres two amounts of hominy. 200/230 = x/100 so x is like 87

Sparky

Good thinking about comparing two amounts, but look at the question again. What is it actually asking you to find? What unit should your answer be in?

Rafael

oh it says what percent MORE so the answer is a percent. so its percent. 230 - 200 = 30 extra and 30/200 = 0.15 so 15% more

Sparky

That's right! You remembered to halve the diameter for the radius. Now for Slide 5, the tricky one! Read it carefully. What type do you think it is, and why?

Rafael

area of a circle again?? bc its round pots and it gives the diameter. so 3.14 x 10 x 10 = 314

Sparky

Good instinct, but the round pots are a trap! Look at the question again: what is it actually asking you to find? Is it asking for the area of anything?

Rafael

no its asking how many liters the small pot holds. and it says proportional to the diameter so its a proportion. 30/9 = 20/x so 30x = 180, x = 6 liters

Named the trick slide as a proportion after one question

At the end, Sparky asked how he could tell the problem types apart, and Rafael wrote: "i looked at what the question asks for and the unit." He added that the round pot tricked him because he saw a circle and didn't read the question.

Rafael is an example student, and Sparky's replies are shortened. The chat skips slides 1, 3 and 4, which he got right on the first try.

What Flint did for Rafael

• When Rafael said he cooks with his grandmother, Sparky made his five review slides about tamales, pozole and tortillas.
• When Rafael set up the percent problem as a proportion, Sparky asked what the question asks for and what unit the answer is in, and Rafael found "percent more" himself.
• After Rafael got the tortilla slide right, Sparky sent him to a round-pot slide that looks like circle area, then pointed him back to the question when he reached for pi.

A teacher can't do this by hand for 30 students, and Sparky does it in every student's chat.

The activity page shows who still picks a method from the numbers

While the class works, Needs attention shows the teacher which student is stuck and on which message. After three or more students submit, activity analytics lists what the class did well, where students went wrong, and a follow-up to practice next.

Set up the activity for free

Open the interleaving activity in Flint's public library, select Use activity to copy it into a free Flint account, and assign it to a class. Sparky makes the slide deck in each student's chat with the activity's default settings, so there is nothing extra to turn on. Before you assign it, open the activity's Preview tab to try it as a student. To review a different unit, replace the four problem types in Guidelines for Sparky with your own, such as slope, unit rate and the Pythagorean theorem.

For quizzing from memory between mixed practice sets, see how to use retrieval practice. For more test prep activities, see Flint for test prep.