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Paul McCrory, In defence of the classroom science demonstration
This article is intended to present a robust defence of the use of demonstrations in the classroom by identifying some of their unique and powerful benefits – practical, affective an cognitive.
Some of the most common criticisms and challenges facing classroom science demonstrations include:
Lack of time or equipment;
Fears that the demonstration may not work;
Concerns about the perceived safety of more spectacular demonstrations in an increasingly litigious environment;
Accusations that ‘whizz bang’ demonstrations give a misleading and damaging impression of what scientist really do;
Pervasive belief that passively watching a demonstration is less effective than conducting a hands-on practical experiment;
Concerns about the lack of evidence of what students actually learn from demonstrations.
There are there main threads to this argument defending science demonstrations in the classroom: the logistical case; the affective case (emotions and attitudes); and the cognitive case (knowledge, understanding and skills).
The case for the defence
The mundane logistical case
The normal justifications given for demonstrations are that, in many cases, they are cheaper, quicker, easier, safer and less disruptive than having each student do the related practical investigation. They come from the widespread philosophy that, explicitly or implicitly, believes demonstrations are easier-to-organise poor substitutes for hands-on practical activities. I believe that this hasty assumption, however, does a great disservice to the true power of classroom demonstrations.
The easy affective case
Demonstrations can be emotionally engaging science theatre. Students who are strongly self-motivated in science can sustain their attention through these moments of boredom. Many students, however, cannot delay their gratification in this way: without first emotionally engaging them to secure their attention, no cognitive outcomes can possibly follow.
Capturing and holding interest
The novelty, spectacle and inherent drama of a classroom demonstration can provoke significant interest from students. Psychologists call this kind of interest situational interest, it can be extremely powerful while it lasts. Situational interest can progress to a more enduring, but personal, form of interest – individual interest. The almost universal nature of situational interest, however, can create exceptionally powerful and intense moments of complete focus. This group dynamic stems from social facilitation, where we tend to take our lead from the attention given to a situation by those around us.
If the emotional engagement derives from a showmanship device that is external to science, then I would agree that such external hooks need to be used very judiciously. If, however, the engagement arises from hooks that are inherent to science, then I find this criticism harsh.
Exploiting the primitive power of curiosity
Scientists are frequently driven by a powerful curiosity about the world, and being curious is a scientific attribute to be valued in its own right. Demonstrations are perfectly suited to exploiting curiosity, the powerful engine driving most of our learning.
Sharing your passion
Students, like theatre audiences, enjoy shared emotional experiences. Demonstrations can emotionally engage your students and reveal your passion for your subject. Your students will feel wat you feel, this is known as emotional contagion. By exposing your genuine enthusiasm for science through demonstrations, you are undeniably making yourself vulnerable to mockery. It is precisely the risk and truthfulness inherent in this self-disclosure, however, that makes your performance so watchable to your students.
The tricky cognitive case
I would respectfully suggest that students learn much less from any particular lesson than we would like to accept. The non-intuitive and abstract nature of most scientific principles, combined with the stubborn resistance of our brains to abandon our misconceptions, makes cognitive learning from a single exposure to any teaching strategy highly unlikely. This applies equally to demonstrations as it does to any other technique.
Showing authentic, concrete and memorable phenomena
Demonstrations should transparently and convincingly show authentic phenomena, ‘take nobody’s word for it’. Demonstrations can help students to observe phenomena with their own eyes. Sadly, however, it is not always straightforward to let them observe precisely what you want them to see.
Provoking interaction, through and discussion
Many demonstrations are based on surprising or counter-intuitive outcomes that provoke thought from students as the try to align the result with their expectation. This cognitive conflict strategy requires careful management so that the conflict between the outcome and their misconceptions is made explicit. Encouraging students to publicly predict the outcome greatly increases the suspense and emotional jeopardy of any demonstration. PREDICT – OBSERVE – DISCUSS – EXPLAIN
Developing scientific thinking skills
The high degree of control that you have when delivering a demonstration allows you to talk your thoughts aloud and ask questions as you explicitly work through the various stages and problems of an ‘experiment’. It is perhaps more realistic to deconstruct these complex skills through a demonstration, than it is to expect students to somehow distil them when they are caught up in the hands-on excitement and distraction of making their own pseudo-experiments ‘work’.
The clinching argument
The separation of the defence of demonstrations into affective and cognitive arguments is artificial and close to meaningless. It is impossible to separate cognition and affect in the brain (Damasio, 2006). The stark, uncomfortable implication of this research is that, if you ignore this affective aspect of your teaching, you will inevitably damage the potential cognitive outcomes your students can achieve.
Summing up for the defence
Demonstrations are tools. Like any tool, they have strengths and limitations and you need to understand these factors in order to use the tool effectively with your students. Demonstrations can be emotionally engaging science theatre. Like theatre, demonstrations have enormous potential to: create and sustain interest; stimulate curiosity; communicate and share emotions; reveal phenomena by showing, not just telling; direct focus; and provoke further interaction, thought and discussion.
We should stop thinking of demonstration solely in terms of their direct impact on cognitive outcomes. If only learning were that simple and quick.