Using Worked Examples to Reduce Cognitive Load in Physics

Learning how to solve problems is the key to becoming a physicist (here and here). The problem with problem solving is that you need to be pretty knowledgeable before you can make a good go at it. And we tend to teach new information and then put it into a problem in the same lesson. This doesn’t work for most learners.

The science of learning – cognitive load theory – has found the best way to to teach problem solving: worked examples.  Hattie puts the effect size of worked examples at 0.57 – 7 months extra progress per year.

When a teacher models how to solve a problem, she is giving the guidance that novice physicists need. She will make the hidden process of solving the problem visible. It is a way in.

But then what? The jump from seeing someone do it to being able to do it yourself is still big.: “novice learners reach apoint of working memory overloadvery quickly” Hattie, Yates. 2014). Learners need a bridge.

One method is to give learners partially completed problems – this method is called problem completion. This reduces the cognitive load, allowing the learner to focus his working memory on fewer aspects of the problem.

Here is an example:

Worked Example

AQA June 2016

Teacher’s explanation

Imagine you are standing at the board – ideally the question is projected adjacent to where you are explaining and making notes for the class:

1. The weight of the ball is independent of the ball’s speed – it doesn’t change.
2. The drag on the ball increases as the ball accelerates.
3. The ball stops accelerating when the drag matches the weight – it has reached terminal velocity.

Completion Problems…

Going straight from worked example to whole questions is very challenging for most learners. Sentence starters reduce the cognitive load:

On 14 October 2012, Felix Baumgartner created a new world record when he jumped from a stationary balloon at a height of 39km. Above the Earth’s surface. 42s after jumping, her reached a terminal velocity of 373 m/s. Explain in terms of weight and drag how terminal velocity is reached.

 

1. The weight ________________________________________________________________________
2. The drag __________________________________________________________________________
3. When the drag has increased _____________________________________________________

One completion problem will not be enough. You will need lots. There are plenty available in past papers, however, there is a cognitive advantage in including individuals in the class:

When his balloon experiment began to go wrong, Mr Rogers knew he had to jump. He was 5km high. Explain in terms of weight and drag why he reached terminal velocity as he fell.

 

1. The weight ______________________________________________________________________
2. The drag ________________________________________________________________________
3. When the drag has increased ____________________________________________________.

Other insights from cognitative psychology include spacing out the practice and interleaving. I suggest revisiting these problems regularly and mixing them up with other questions. Aim for success – there are benefits for students getting it right. Optimum challenge is great, but getting answers wrong makes it more challening next time.

In my next blog, I will describe another strategy for reducing the cognitive load for novice physicists – cooperative learning.
I found @olivercavigiol teachinghow2s.com helpful in writing this blog.