K3.4 Doing Demonstrations
This article has been added at the suggestion of colleagues at the ATSE conference at Nottingham (August 2008). Within a context of 'how science works' it aims to explore the rationale for including teacher demonstrations in the science curriculum and to provide detailed notes on a number of demonstrations (mainly chemistry) that have been used successfully. A bibliography of other sources is also provided.
Each demonstration contains practical advice, safety and risk assessment notes and connections to the key scientific ideas provided by the demonstration. (These are available as downloads.) Should you wish to add you favourite demonstrations to the compilation please contact email@example.com.
Standards: This unit specifically relates to Q14 but, appropriately used can contribute to and provide evidence of competence for many others of the standards especially Q4,6,7,8,18, 22 and 25.
Keywords: Secondary, How Science Works, Practical work, Demonstrations, Safety, Teacher Engagement.
K3.4 Doing Demonstrations (Mainly Chemistry)
The ‘How Science Works' dimension of the new programme of study for science at KS4 recognises the importance of ‘modelling' the processes of ‘doing science' throughout the full breadth of study.
The main headings of these are presented below - but for the detail it will be necessary to refer to the original publication. (QCA, 2006.)
How science works:
- Data, evidence, theories and explanations.
- Practical and enquiry skills.
- Communication skills.
- Applications and implications of science.
Breadth of study:
- Organisms and health.
- Chemical and material behaviour.
- Energy, electricity and radiations.
- Environment, Earth and universe.
This represents a useful list of processes, skills and issues to be included in the science education enterprise and will be valuable in evaluating science programmes to gain assurance that these aspects are explicit.
Personally I have some significant problems with the presentation and particular worries about the ways they may be interpreted by teachers, inspectors and examiners. I have separated the exploration of these into a short download (Download K3.4_1.0a_How Science Works) and it is sufficient here to remark that there is little focus on the process of asking questions. In addition it is important to recognise that the clauses ‘pupils should be taught' and ‘the following should be covered' that infect the whole of our national curriculum - can only be valid if the pupils are personally and critically engaged in a learning enterprise. It is particularly unfortunate when these often repeated words from our national curriculum are interpreted as ‘the pupils must be told' and when success in learning science is measured by only or mainly by examination results. Accepting information merely because it comes from ‘an authority' or learning meaningless words and/or formulae just for an examination, although we have all done it on occasion, represents a failure of the science process. Such uncritical learning is anti-scientific.
The thesis of this article is that our pupils should experience science as a lively, exciting, meaningful and personally engaging subject. We as teachers should aspire to engage in its learning with our students - we need to know and understand a great deal of science, but some of our pupils will inevitably have different experiences and will know things that we do not. Some of our students may well be intellectually more able than we are and should be able to challenge and develop our understandings as teachers. One thing seems clear: that if students are to become active science learners more of them must be encouraged to interact critically with their science curriculum. (Goodwin 2001) They must be encouraged to ask questions, seek for and evaluate evidence and become convinced about the correctness and value of the science they are learning. In short, learning science must become more like doing science. A recent issue of School Science Review (March 2007) recognises the importance of this and focuses upon ‘Argument, discourse and interactivity'. The focus of these papers is on doing teacher demonstrations with our pupils. This is one way in which we can engage in interesting and engaging science, share our enthusiasm for science, raise questions and provide evidence.
Download K3.4_1.0b_Science and School Science is a short note relating to the tension between learning science (that the scientific community accepts as being ‘correct') and the more uncertain aspects of applying ideas to the complex, but very small, world in which we live with other people and with other species of living things.
Science learning needs to be both meaningful and memorable. There are a good number of practical experiences that it is inappropriate for students to carry out themselves either because the process is too expensive, too complex or too hazardous. Often more than one of the above constraints applies. However, an experience does not have to be dangerous, expensive or complex to be worthy of demonstration - a quick demonstration is often useful as a conclusion to a class practical (especially if students have ambiguous results), before a class practical (although take care not to reduce the impact of the practical - the students must not just be doing it again!) or for revision. It may not seem much of a demonstration, but simply showing a large number of compounds of transition elements to students at KS4&5 can help justify the statement that most compounds of such elements are coloured - and raise questions as to whether zinc should be so classified.
By organising suitable demonstrations it is often possible for students to enjoy a really educational experience whilst minimising expense, complexity and hazard. Perhaps, more importantly, it also gives them the opportunity to share the teacher's more extensive science expertise AND observe the teacher engaging with his/her own subject knowledge and with the processes of ‘How Science Works'. The use of exciting science teacher demonstrations in the curriculum has declined markedly since the 1980s (reasons may include: introduction of the national curriculum (Donnelly and Jenkins; 1999); inappropriate emphasis on health and safety, concern for the litigious society should anything go wrong; belief that only pupil practical is effective; lack of teacher experience of demonstrations in his/her own science education; only marks in tests and examinations are really valued.) This decline may not be the only reason for the fact that pupils seem now to find science in general - and chemistry in particular - one of the most boring subjects on the curriculum. (Osborne and Collins; 2001). Whatever the reasons, it seems clear that for many pupils and teachers learning/teaching science is now less meaningful and less enjoyable than it once was.
The use of teacher demonstrations in science lessons can:
- Help to expand the pupils first hand experience of scientific phenomena and observe a more experienced scientist working with chemicals, equipment and ideas.
- Free the pupils from the need to ‘take care' for themselves and to observe critically the teacher's practical skills. They should all observe the same outcome from the experiment and this helps generate focussed questions and can make the experience more meaningful.
- Encourage pupils to explore with their teacher ‘how science works'. Demonstrations can sometimes be altered or extended to capitalise on pupils' questions or suggestions.
- Allow pupils to see that science teachers enjoy ‘engaging' with science. (It must be more than ‘just having fun.')
Many of the examples in this collection are unsuitable for individual or group practical work, although senior students and/or technicians might use some of them for demonstration during open days or parents' evenings, or possibly for more detailed project work. Some are indeed quite spectacular but, if we are considering science education, the key concern MUST BE to encourage thinking or learning about specific scientific ideas, processes, applications or issues. Hopefully the experience will also be enjoyable and entertaining, but the purpose is to engage and explore scientific thinking, doing and understanding.
Objectives relating to safety and survival are even more important than educational ones. It is important to ensure that risk is minimised and that you are familiar with the reaction and the procedures involved before demonstration to an audience. (However, don't practise in private - make sure there is someone else around just in case something does go wrong and you need help. This advice applies to any potentially hazardous activity including DIY.) Practice makes perfect, but do not allow familiarity to breed contempt! You must be prepared to take responsibility for the demonstration before you attempt to do it.
Each demonstration is presented as a discrete example with:
- A descriptive title
- An explicit description of a possible way of carrying out the demonstration, including a diagram where appropriate. (There may well be better ways of doing this for you in your context, with the equipment you have and with your specific skills.)
- An outline and annotated ‘risk assessment'. Again it is important that you validate this for yourself in your situation. You must make your own assessment of risk before carrying out the demonstration yourself.
- Some hints as to possible education contexts, which relate to, justify and/or lead from the experience of the demonstration.
These materials are always in DRAFT form, thus any suggestions for improvement or for additional demonstrations are always welcome)
Draft 11: June 2010
Donnelly J F and Jenkins E W (1999) Science Teaching in Secondary School Under the National Curriculum (Leeds: Centre for Studies in Science and Mathematics Education, University of Leeds.)
Goodwin A (2001) ‘Wonder in science teaching and learning: an update.' School Science Review, 83 (302) pp 69-73.
Osborne J and Collins S (2001) "Pupils' views of the role and value of the science curriculum: a focus group study." International Journal of Science Education, 23, (5),441-467.
QCA (2006) http://www.qca.org.uk/12265.html (Full KS4 science specification can be downloaded from this site.) (Accessed 6th April 07)
School Science Review (2007) ‘Argument, discourse and interactivity' March 88 (234)
Farley R F (2001) School Chemistry Experiments - a collection of tried and tested experiments for use in schools. Hatfield, The Association for Science Education.
(A very useful collection of material - both for demonstration and class use - applicable for KS3, 4 and some at A-level. For quantitative experiments a specimen set of results is usually included.)
Fowles G (1957) Lecture Experiments in Chemistry (5th Edition) London, Bell.(This is a classic publication - now considerably out of date - but still contains a wealth of ideas)
Grundmeier E W (1993) Chemical Magic (2nd Edition) - this is a revised version of an original 1959 text by Ford L A - New York, Dover Publications. (This little book is written with little concern for the use of dangerous chemicals although it does stress the need to ‘be careful'. As a source of some good ideas it can be recommended, but it is vital that careful risk assessments are performed independently. You will appreciate that I do not like the title.
Hutchins K (2000) Classic Chemistry Experiments: one hundred tried and tested experiments. London, Royal Society of Chemistry. (£27.50)(This is a companion volume to Lister's book of demonstrations given below. Specimen work sheets are given in a number of different formats. Some of the experiments given would, in my opinion, best be used as demonstrations; indeed some are given in both volumes. Nonetheless there is a wealth of useful material here.) Copies of the student worksheets from this publication are freely available from http://www.chemsoc.org/networks/learnnet/classic_exp.htm.
Lister T (1995) Classic Chemistry Demonstrations: one hundred tried and tested experiments. London, Royal Society of Chemistry. (£27.50)(There are some really exciting demonstrations here - a basic set of ideas for all science teachers at secondary school. There will be some you probably would not wish to use and you will wish to extend your repertoire. However, this seems to be a good place to begin.)
Seah WK, Lim MK, Lee FG, Ong TSR, Yeo NWX, (2008) "cheMagic: 50 Chemical Classics and Magical Tricks" Singapore, World Scientific Pub. Co. Pte. Ltd. This is an interesting selection of chemistry demonstrations with some good ideas at different levels of sophistication. The printing of the illustrations is not particularly clear and the authors go out of their way to emphasise the 'magic' and entertainment aspect and hide the chemistry. (I would try to use the demos differently. Some appropraite hazard warnings are included, but some of the techniques suggested - such as dipping fingers into sodium thiocyanate solution (p120) are certainly not recommended.
Shakhashiri B Z (1982-92) Chemical demonstrations : a handbook for teachers of chemistry. - Madison; London: University of Wisconsin Press.(This represents a series of books written and published in four volumes for the American ‘market'. They are excellent, but originals are very expensive >£120 for the set.)
Web Resources. These are widely available and a good place to start may be http://www.liv.ac.uk/Chemistry/Links/links.html. A particularly relevant site from the University of Leeds is: http://www.chem.leeds.ac.uk/delights/texts/ (Details are provided for over 40 spectacular chemistry demonstrations. This forms an excellent resource with full details of a range of demonstrations, with references and animated photographs of many of the demonstrations in progress. Many of the demonstrations are described elsewhere too.)
1 A Giant Bunsen Burner
2 The Exploding Can (A)
3 Exploding Bubbles
4 Flares from Combustible Powders
5 The ‘Blue' Bottle
6 A Hydrogen Balloon
7 An Oscillating Chemical Reaction
8 Selective Dyeing
9 Photographic Dyeing
10 An Iodine ‘Clock' Reaction
11 The Carbon Disulfide ‘Flash'
12 Colour with Polarised Light
13 ‘Elephant's Toothpaste' - Catalytic Decomposition of hydrogen peroxide
14 Many Liquids from one bottle
15 The Howling Jelly Baby
16 The Exploding Can (B)
17 An ‘eggsperiment' and floating bubbles
18 ‘Flash-back' with an inflammable solvent vapour
19 Ammonium Dichromate ‘Volcano'
20 Fire Trails
21 Spontaneous Combustion
22 Gas Reactions using Disposable Syringes
23 Silicon and Silane
24 A Magnetic ‘Particle' Accelerator
25 Catalytic oxidation of Ammonia using Cr2O3
26 (15.1) Flame tests on a large scale
27 Iron gains weight when it burns in air
28 Dehydration of sugar - and a version of 'pharo's serpent'
Published: 17 Oct 2008, Last Updated: 30 Aug 2009