The Use of Demonstrations in Science Teaching

A couple of weeks ago, I took part in a live recording of the Guardian's Science Weekly podcast which was also filmed for the Royal Institution's Ri Channel.

Guardian Science Weekly Live from The Royal Institution on Vimeo.

My friend and former teacher Dr Michael de Podesta has written a kind of review of the podcast which prompted me to put up this blog post in which I want to share some notes I made on doing science demonstrations as part of my work as a Nuffield Education Fellow last year:

Demonstrations, like whole class practicals, are an "activity which involves at some point the students in observing or manipulating real objects and materials". Like whole class practicals, demonstrations can be made more effective by proper planning and having clear learning objectives in mind. In his essay The Art of Effective Demonstrations, David A. Katz says, "An effective demonstration should promote good observation skills, stimulate thought, arouse curiosity, present aspects of complex concepts on a concrete level, and, most important, be the basis for class discussion"

Demonstrations provide an opportunity to engage students in a different way to other types of lesson activity, in particular, they can provide an opportunity to insert some drama and entertainment into your lessons. Dr Paul McCrory, in his essay "Developing Interest in Science Through Emotional Engagement" writes: "There is a very wide range of positive emotions which teachers can foster through the way they teach science - for example, curiosity; anticipation; uncertainty; surprise; intellectual joy of understanding; wonder; sense of imagination; amusement; sense of beauty; and amazement… Developing positive emotional responses in the classroom also helps to cultivate effective relationships between the teacher and the pupils."

In some situations, it may be more appropriate and indeed more effective to carry out a demonstration instead of carrying out a class practical - for example, students have traditionally observed Brownian Motion in lessons where they individually (or in pairs) use a smoke cell and microscope to observe the phenomenon. This video shows how the same practical can be done more effectively as a demonstration.

Learning Objectives
As with all practical work, be clear what it is you want your students to learn from the demonstration. Ask your self "why am I doing this demonstration?" and "What do I want my students to learn?"

Encourage Discussion and Questioning
This is perhaps the single most important thing to bear in mind when carrying out a demonstration as part of your lesson. Ask the audience to explain what happened and why and, if necessary, guide students to the correct answer. Asking your students "Predict, Observe and Explain" or even "Predict, Explain Prediction, Observe and Explain Observation" can be a useful way to structure your demonstration.

Preparation and practice
a) Make sure the demo works. If you end up having to say "X should have happened here", it defeats the point of doing the demo and can makes you look a bit stupid to your students. This means preparing the demo properly and practising it repeatedly to make sure that it is reliable.

b) Make sure the demo works well. There's a world of difference (and a lot of effort) between a demo that sort-of works, and one that works really nicely. Find the time to practice and rehearse the demo properly so that you are confident in managing all of the things which you need to do automatically and can therefore focus on interacting with the pupils when presenting the demo.

Learn from each "performance" and incorporate the "happy accidents" and interactions which spontaneously occurred into your plan for when you do the demo next time - write them down or you will forget these gems.

Visibility
Seems really obvious, but you must make sure that your students can see the demo. if they can't all see you (and the demo) or hear you clearly, your lesson will not be effective. Pay attention to size and lines of sight and carry out the demo from the most appropriate position in your classroom - which is not necessarily the front of the class. Ensure that no part of your body obscures your students' view. If you have them, use "demo" versions of standard apparatus, for example, large ammeters in physics or large beakers for reactions in chemistry. You can make small demonstrations easier to see by using a video connected to your whiteboard.

Focus student attention
Prepare students to observe what you want them to see with effective discussion beforehand. During the demonstration, bring their attention to the things you want them to see.

Repetition
If possible, repeat the demonstration - this will allow you draw attention to things students may have missed first time. It will also allow you to tease out students' hypotheses about what is going on and help refine their observational skills. It also allows you to highlight things that may come up in discussion.

Involve students
If it is safe to do so, get a volunteer to carry out the demonstration.

Showmanship
You can engage your students attention and enhance their enjoyment of your lessons by indulging in some showmanship with a demonstration. David A. Katz advises teachers to "Show surprise at the results. Show dismay at demos that go particularly slow. Presenting demonstrations is fun. Ham it up with props, costumes, funny signs or slides, jokes, etc… If you are enjoying yourself, so is your audience."

Explanation
Make sure you know the correct explanation for the demonstration. Many popular websites etc. contain inaccurate or even entirely incorrect explanations for popular demonstrations so research the science behind the demonstration properly, from "serious" educational sources. If possible, and if appropriate (often much better), "work out" the explanation with the class.

Summarise
Ensure that you go over what students were supposed to see from the demonstration and learn from the explanation. Ask your students, "what did you learn?" The discussion at the end of the demonstration is essential and you should plan your lesson to guarantee that there will be time for it.

Coping with Failure
Sometimes, even with the best preparation, demonstrations do not work as planned. There are number of ways you can deal with this, including having a second go (if time and resources allow) or showing a video of the phenomenon. A "failed" demonstration may provide you with an opportunity to discuss with your students why the demonstration didn't work.

Safety
As with all practical work, ensure that you have done a risk assessment. Check your apparatus beforehand and use safety shields and goggles where appropriate.

The above notes have been inspired and informed by the work of David A. Katz, Dr Paul McCrory, Dr Ben Craven, Jonathan Sanderson, Elin Roberts and many others.