WEBVTT

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I'm Ken Koedinger.

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I'm a Professor of Human Computer Interaction and Psychology here at Carnegie Mellon University.

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The idea of alternating worked examples is that often, students are given homework problems,

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for instance, where it's all problems-like 10 problems that they solve

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and they often don't have enough information.

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They get stuck when they are at home.

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Maybe they can ask an older brother or parent, but a lot of research has shown that instead

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of having 10 problems to solve, if students had every other problem with an example of how

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to solve that problem-worked-out example of how to solve it

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such that they had five examples alternating

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with five problems-they learned much more from that.

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And that's the key idea and it's actually a very powerful idea

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because it's very simple to implement.

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One thing that can happen with a single example-and this is trying

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to illustrate why it's important to have multiple examples-is I can get the wrong idea

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from an example, so let me take a very simple Algebra equation: 3x = 9.

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And we all know the answer is x = 3, but if I am just learning that,

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what might I think from that example, 3x = 9, x = 3?

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Well, one thing I might think is, you took the 3 from 3x and you brought it

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over to the other side and if that's what I look at that example and say, "Oh,

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I got it," then when I get 4x = 12, now I say, "Oh, just like the other one, x = 4."

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No, x = 3, but the first example made me think that it should be 4,

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that I just copied that number over.

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By having two examples, now I contradict

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that misconception I might have gotten from just one example.

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And I think that too often the textbook gives us one or two examples,

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where we can learn from those two examples something that isn't right,

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that's not going to work in general.

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So by having more examples, it really helps me to see "Oh, no, I had the wrong idea."

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The right idea-the deep concept here-is the one that's consistent across all of these examples.

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This idea of alternating worked examples and problem solving is really a general idea.

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A lot of the studies have been in math and science, but this really can work in many areas.

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The benefits are really of two kinds that the research has identified.

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One is that students learn these ideas more deeply and are therefore better able

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to transfer the knowledge to new problems, to future learning opportunities.

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They are not just stuck locally.

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Sometimes, students can learn just enough to pass the test,

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but what this technique is showing is that you can really help students to get more than that,

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where they really understand what they are doing.

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The second one is that you learn faster and easier.

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It's very consistent results across all of these studies,

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that you get quite big reductions in the time it takes for a student to get to the same

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or better-as I already said, often you get to a better point-but what's really great

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about it is you can get to a better understanding in less time, sometimes 20 percent,

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sometimes like a third less time to get to the same place.

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And that, I think, is really powerful, not just because we want to make kids' lives easier, but,

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of course, it would be great if a student can get their homework done

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in say 20 minutes rather than 30 minutes.

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But it's also because it gives them more time to actually focus on more challenging stuff.

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So, if I am using this as a teacher-so many teachers in math and science courses find

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that they can't get into the more advanced topics because their kids are struggling so much.

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Well, if it only takes four weeks when it used to take six weeks,

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I am going to have an extra two weeks to get into harder ideas and take more challenging topics.

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Having a worked example is like having a tutor in a way.

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Of course, if every kid could have a one-on-one tutor, that's a really powerful thing.

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But it's even more powerful in some ways because a lot of tutors will say, "Here,

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solve this problem and I will help you out."

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But if you're always in this mode of problem solving, so much of your mind is stuck in trying

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to figure out how to do this problem.

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But what we really want out of learning is getting the ideas

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that will help you solve future problems.

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So, problem solving sometimes creates so much, we say, cognitive load-so much of your thinking

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or cognition is involved in trying to get it done-that you don't have enough to reflect

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on what the ideas or concepts or mathematical principles or scientific principles are.

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An example gives you a little more cognitive headroom, if you will,

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to focus on understanding the principles.

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