How do you explain new, abstract and complex ideas effectively in the classroom?
Explanation is the bread and butter of science teachers. We have a large body of scientific ideas that we know and understand and we have to transfer that understanding to our students. Many of these ideas are abstract and complex. Furthermore, the students will also have a wide range of misconceptions that will need to be unpicked before we can begin to successfully build and develop new knowledge.
When thinking about our explanations, there are four questions that science teachers should consider:
How do we tether new knowledge to what students already know?
It is widely accepted in cognitive science that we are more likely to absorb new knowledge if it links to existing schemata.
How can we introduce new ideas in clear steps?
We know from cognitive science that the working memory has a limit to what it can do – known as cognitive load. If we try to present too much information to students at once, there is a real risk that we will overload their working memory, resulting in confusion and a lack of processing.
How do we avoid the curse of the expert?
We have to be incredibly careful when explaining new ideas not to ignore knowledge that we have (and take for granted) that our students will not have.
How do we make abstract ideas concrete?
We need to think carefully about how we can make abstract scientific ideas tangible to students.
Explanation strategies
By answering these questions we arrive at what we can do to put them into action.
1. Science stories
We have a plethora of stories available to us to help explain scientific ideas. Stories work because they take very complex ideas and put them into a very real context that students can understand. The human nature of the stories makes them highly memorable for the students.
For example, tell the story of how Ignaz Semmelweis observed that the incidence of puerperal fever in maternity wards could be drastically reduced by hand disinfection.
2. Find the sweet spot
New knowledge needs to be built upon existing knowledge or schemata. We need to find the ‘sweet spot’ – that is, what they know that is helpful, what they know that is not helpful and how we can build on that. This should inform where you pitch your explanation.
There are a number of ways we can do this. For example, show students a practical demonstration or visual prompt and then use this to probe their understanding of the topic. Or, get straight to the point. Rather than waiting for the students to reveal their misconceptions about science, why not present them to the students straight away and discuss with them which one is right and why the others aren’t?
3. Open the curiosity gap
Young people are naturally curious. As science teachers, we can use this to our advantage at the start of the lesson. Show the students something interesting that will make them curious about the topic and keen to find out more (e.g. the aftermath of the nuclear explosion at Chernobyl). Following this, explain to them that by the end of the lesson they will be able to explain what they have seen. Their natural inquisitiveness should make them want to fill the curiosity gap that you have opened.
4. Make the abstract concrete
As scientists we deal with abstract concepts all the time – for example, the structure of the atom, the particle nature of cells and chemical reactions. These are all things the students can’t actually see, so they need to be able to visualise them if they are going to genuinely understand them. So how can we make these concepts more concrete?:
• Practical demonstrations and experiments. For example, understanding convection as a purely theoretical model is conceptually difficult. However, if the students are shown a demonstration – such as the ‘model mine’ with smoke being carried up and down by the convection currents in the air – it becomes more real, as long as it is supported with effective commentary and questioning.
• Link it to what they already know. Sticking with convection, most students will know it’s often warmer upstairs than it is downstairs. Unpick with them why this is (i.e. because hot air rises). Now that you have made this idea concrete you can then go on to look at the theoretical explanation as to why this happens.
• Use models. As well as to understand processes, models can also be used to explain scale in science. For example, the size of the nucleus of an atom could be compared to a marble in the centre circle of a football stadium, with the stadium representing the size of the atom and a grain of rice in the stands of the stadium an electron.
• Make it about them. Try to make concepts relevant and important to the students as individuals. A great one for this is when looking at cells; nothing will beat a student preparing and observing one of their own cheek cells!
Explain, probe and repeat
When science teachers are explaining new ideas, we do need to explicitly tell students about them in order to share our knowledge. There is nothing wrong with this and, contrary to some recent thinking in education, we shouldn’t be ashamed of this ‘teacher talk’. We know stuff and they don’t, so we have to tell them!
However, the best science teachers are very skilled at punctuating their explanations with questioning and modelling.
Additionally, following our initial explanation of this key learning during the lesson, we should not just leave it there. We should come back to the fundamental learning points at different phases of the lesson, and indeed in future lessons when it links to a related topic and the concept naturally fits in.
This article is a condensed excerpt from Making every science lesson count by Shaun Allison, which contains many more strategies for explaining difficult concepts in science.
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