By Carole Kenrick, Regional Representative in Primary Science, The Ogden Trust and Scientist / Inventor in Residence, Gillespie Primary School


When preparing to host my first ASE Twitter chat in the lead-up to Demo Day, I was brought back to my early days in teaching. I remember, perhaps a month in, asking my technician (a wonderful human being, who once posted chocolate and a get-well-soon-post-it to my house when I was ill with the flu) to help me with a chemistry demo. Being a physicist by degree, whose own school chemistry memories consisted mostly of acquainting myself with a textbook, I felt woefully unprepared to demonstrate the thermite reaction! However, I was determined to do it, because the one positive memory I did have of my chemistry lessons was of this particular demo - the teacher let me keep the lump of iron at the end. It remained a source of wonder and mystery for many years as I had no idea how or why it had gotten into the fume cupboard. Until I became a science teacher, and decided that I must finally get to the bottom of this apparent alchemy – and work out how to make sure demos didn’t leave my own pupils as baffled as I once was.

What follows is a collection of my musings about demos, enriched with the contributions made by colleagues taking part in the Twitter chat. I have kept the questions I posed during the chat as headings and I welcome further thoughts, suggestions and questions on the topic.


Q1: What is the purpose of a demo?

During the twitter chat several people highlighted the benefit of pointing out to pupils what they should be paying attention to, something that can be difficult during a class practical1. It was felt that demos enable pupils to focus more on why something is happening rather than worrying about following a “recipe”, with reference made to the risk of cognitive overload2. Demos were also lauded as a way of engaging, surprising or inspiring pupils, particularly by primary colleagues.

My perspective is that the purpose of a demo depends entirely on what you want pupils to learn from it. I consider demos to be a tool, which I choose and plan with a purpose already in mind. Their purpose can be to surprise, inspire and elicit questions; at other times to illustrate or reinforce a phenomenon or explanation; to learn about how scientists “do” science; or to assess pupils’ understanding and develop it further.


Q2: How can we ensure pupils learn from demos?

Firstly, pupils need to be engaged – by which I mean that they are paying attention to, interested in and curious about what is going on. However, engagement alone is not enough as even engaged pupils will not necessarily understand what they are looking at or know what to “look” for3. We need to scaffold their thinking and model scientific reasoning; questioning along with clear explanations are key to pupils’ learning from a demo.

In Demo: The Movie4 Alom Shaha advocates the “P.O.E.” approach: Predict, Observe, Explain. Asking pupils to make predictions gives them something specific to look for when observing the demo, and motivates them to pay close attention to what is going on. It also enables you as a teacher to anticipate important aspects that pupils may miss if they are expecting something different, and to draw their attention to it. For instance, if pupils are only expecting a colour change they might not notice a temperature change. Following up with discussion of whether they were correct and why after observing the demo enables pupils to explicitly identify changes in their understanding and relate their observations to the underlying scientific principles. With this former aim in mind, one of my favourite reflection tasks requires pupils to complete three sentence starters: “I used to think that… But now I know that… Because…”.


Q3: Is audience interaction important or necessary?

The appropriate level of audience interaction depends on the purpose of the demo as well as the age, prior knowledge, understanding and context of your class. In some instances, you may consider questioning pupils to be enough, at other times involving pupils in the demo as assistants or evaluators can be beneficial. I have certainly found that pupils rise to the challenge and find it highly motivating to be given the responsibility of my assistant.

When teaching circuits one of my go-to starting points is to warn pupils that I was in such a rush setting up this demo that I think I may have wired the circuits up incorrectly. And so, the pupils must problem-solve and suggest how to fix them. This is both an enjoyable exercise and makes it less likely that they will make these mistakes themselves when carrying out their own class practical work.

At the other end of the spectrum I have carried out and observed other teachers performing silent demos with exaggerated motions, intense facial expressions and dramatic pointing. In this case the interaction is non-verbal, but the effect can be dramatic – I stop the second a pupil speaks so they stay silent – making them pay incredibly close attention to every detail.

Several contributors to the Twitter chat also advocated for silent demos, as well as children leading demos – something that may well have the bonus of developing their perception of themselves as scientists5.


Q4: How can teachers improve demo “performance”?

 There is no short-cut - unfortunately for those new to teaching or to demos the consensus is: the more you do it the better you get so practice, practice and practice some more! Every time you carry out a demo in front of pupils you will get better at anticipating issues, questions, points of confusion, and how to address the alternative frameworks that pupils may have and through which they interpret what they see. You will also find ways of building suspense, creating the element of surprise and focusing pupils’ attention on what you want them to notice.

Whilst it can be tricky to find the time to rehearse demos, it is essential. If possible schedule some time with a technician if you’re a secondary teacher, or make a practice date with a colleague/other local science lead if you teach primary. In an assembly last year, I demonstrated why space craft need heat shields using the help of Tim-eggy Peake and a chef’s blowtorch. I planned and practiced this in advance with a local science lead – together we worked out how to set it up, how to introduce it, which questions to ask and how to safely fill and use the blowtorch. We bounced ideas off each other and saved time and money by sharing resources.

Demos can also be a brilliant opportunity to introduce stories about the history of science, how scientific ideas develop or to make links to the applications of science. Finding out about these takes time but they are crucial to develop pupils’ understanding of and opinions about science. Such stories are part of my “bank” of pedagogical content knowledge6 that I top up through conversations with colleagues, reading books, watching videos on YouTube and documentaries about science. A recent example is the programme about Maxwell, currently available on iPlayer7, which I have watched twice (the second time I took notes!). I love the suggestion made during the ASE chat of a “demo spot” during department meetings to share ideas, something that could also be done during staff meetings in primary schools.


Q5: What good resources are out there for demos?


  1. Analysing practical activities to assess and improve effectiveness - Robin Millar
  2. The science of learning
  3. The Pupil as Scientist? - Ros Driver
  4. Demo the movie
  5. ASPIRES report
  6. Pedagogical content knowledge
  7. Maxwell programme


Carole Kenrick

Regional Representative in Primary Science, The Ogden Trust

Scientist / Inventor in Residence, Gillespie Primary School