Clear Teacher Explanations I: examples & non-examples

The phrase “too much teacher talk” scrawled across lesson observation forms seems to be on the decline (at least, according to my Twitter feed). Teachers are abandoning ineffective discovery-based approaches, and harnessing the power of teacher-led, explicit instruction. I like to imagine sages around the country getting onto their stages and unashamedly explaining the marvels of their disciplines; lightbulbs pinging atop their pupils’ heads more frequently and brightly than ever before…

However, when I hosted the #MichaelaScience conference in July 2019, I asked attendees the following question: Have you had training on improving the quality of your explanations in the last 6 months? More than 80% had not. Considering that teaching involves a lot of explaining (I presume this is an uncontroversial claim, but you never know…), I was understandably flabbergasted.

Survey Poll 2

Given how important explanations are in teaching, this result surprised me.

In this series of blogs, I aim to share different strategies for improving teacher explanations. Of course, teaching is far more than just giving explanations, but it’s an important component that isn’t given the attention it deserves. Clear Teacher Explanations will be broken down into four parts:

  1. Examples and non-examples: concrete to abstract
  2. Dual coding (Part a on processes, Part b definitions & complex concepts, Part c on procedures, Part d on depictions of real life, Part e on visual models & Part f on common mistakes teachers make on dual-coding).
  3. Presence in the classroom: body, eyes & voice
  4. Keep them hooked with Assessment for Learning

Most examples I use will be science-y, but the ideas apply to any subject where abstract ideas need to be explained well.

Concrete examples pave the way to understanding the abstract
When I used to teach homeostasis in Biology, I used to give my pupils the definition: ‘Homeostasis is the maintenance of a constant internal environment’. I now think this is an ineffective to begin a lesson. By starting with a generalised definition, I am presenting a vacuous string of words, devoid of meaning.

At Michaela, Science teachers always begin with concrete examples:

  • “Imagine you are exercising. Your body temperature goes up. How does your body respond? You sweat, cooling your body down. On the other hand, on a cold winter day, as soon as your body temperature goes down, your muscles start shivering which warms you back up. So, when your body temperature goes up, your body does something to bring it back down. When it goes down, your body does something to bring it back up.”
  • “What happens if your drink too much water? You may need to visit the loo more often – you urinate more. What happens when your body loses too much water, say on a really hot day? Well, you feel thirsty to increase your water levels. So: when your water levels go down, your body does something to make it go up and vice versa.”
  • “We call things like ‘body temperature’ and ‘water levels in the body’ our internal environmentbecause they are conditions insidethe body that might change.

The first two bullet points are specific examples of homeostasis. They are really easy to understand because they are so concrete – pupils will have experienced them so know exactly what they mean. They won’t have come across phrases like ‘internal environment’ or ‘maintenance’ in the context of Biology before, but can begin to make sense of them in reference to the examples used.

What makes concrete examples so useful is that they give pupils something to think about when they encounter the generalised definition. As they read the word ‘maintenance’ they can think (or can be directed to think), ‘Ah, when it goes down, the body brings it back up like with temperature’. When they read the phrase ‘internal environment’ they are thinking, ‘Ah, like temperature or water levels’. If pupils were not presented with those examples, they would have nothing to link the definition to so would not be able to comprehend it. A generalised/abstract definition without reference to something specific and concrete is devoid of meaning.

Non-examples highlight concept boundaries
Imagineyou are teaching the idea of condensation by using the following examples: steam on the bathroom mirror, breath on a cold window, water droplets on the lid of a saucepan on the stove. All of these examples have two features. Firstly, they share the core featurethat you want pupils to generalise: a gas turning into a liquid as it is cooled. The second feature all of the examples share is ‘water droplets on glass’. However, this is not the core feature that we want pupils to generalise; it is a surface featurethat happens to be shared by the examples used. Since pupils have a tendency to generalise from the examples they are exposed to, there is a real risk that a pupil wrongly believes that raindrops on a window is also an example of condensation.

How can we avoid such misconceptions? By explicitly sharing ‘raindrops on a window’ as a non-example. Doing so makes it clear to pupils that it is not the idea of droplets that is important, but that of a gas becoming a liquid, which is absent when a raindrop hits a windowpane.

It is powerful to contrast an example with a non-example which shares surface features to illustrate the difference between the core and surface features.

Examples non examples

It is important to use several examples to highlight the shared features which you want pupils to generalise. Non examples highlight the boundary of the concept.

Examples should sample a wide domain
The final key idea about the use of examples to teach abstract concepts is to use a wide variety of examples. If you are teaching natural selection and only refer to camels, polar bears and poisonous frogs, there is a risk that pupils think natural selection only happens in animals.

If you use examples to include animals, plants and bacteria, then you are truly sampling examples from the breadth of the domain (entire scope of the topic) that is natural selection.

How many examples are sufficient?
You have to test your pupils’ understanding to determine how many examples are sufficient. After a few examples, ask application questions – do they succeed in applying the concept? If they cannot, it is likely they require further examples. If they do succeed, then ask a few more questions that require them to apply the concept in a trickier scenario.

E.g. Gaseous molecules of oil become liquid molecules of oil upon encountering a cool worksurface, causing it to become greasy. Is this an example of condensation?*

You can never really be sure they get it fully. But the more questions you ask, the more certain you can be that they ‘get it.’

Questions to ask yourself when you are planning:

  1. How can I introduce a concept through concrete examples, before using the abstract generalisation?
  2. Are there non-examples that I can use to help illustrate the boundary of the concept?
  3. What misconceptions could my sequence of examples/non-examples throw up?
  4. What questions can I ask during my explanation to check for successful comprehension?

Then find someone to practice your explanations with! This won’t always be possible, but I find that this is when you can gain the best insights into how to teach the concepts you want to teach.

To answer the above question on condensation:
*If you are thinking ‘yes’, then you are right. If you are thinking, ‘no’, then it could have been because my examples from above were limited to water and glass only, and you wondered whether condensation applies to other substances. In this case, you know that more examples/non-examples are required.


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14 thoughts on “Clear Teacher Explanations I: examples & non-examples

  1. I would venture that there is more to condensation than you imply. Change of state is a broad topic as demonstrated by a recent tweet asking how such might be taught in an assigned English classroom (ie little equipment)

    I have inherited CJ Smith’s 1933 Intermediate Physics text and it is interesting to consider its (traditional) relevance to my primary STEM class tomorrow. I prefer less Q&A more practical.

    I look forward to your next blog


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