1 Why use demonstrations?
For your students to be fully involved and participating actively in lessons, you may think that they should always learn by doing. Certainly students should be given the opportunity to carry out practical work in science themselves. This gives them the opportunity to develop skills in handling and using equipment, making decisions, collecting data and actively thinking about what they are doing and learning.
Demonstrations offer useful opportunities for purposeful participation in learning that can enhance understanding of the concepts given in the textbook. Leading science educators make the point that there is always a place for an ‘interesting, sometimes unforgettable, demonstration that may form an important episode in a student’s learning’ (Wellington and Ireson, 2012).
 Pause for thought
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A demonstration provides a shared experience that allows you to focus your students on particular aspects that they might otherwise miss. You can use demonstrations to support your explanations and scaffold your students’ understanding. For example, when teaching about food, a demonstration could develop students’ observations on how food changes when it is cooked.
There are other good reasons why students cannot do the practical work themselves. For example, with large numbers of students, the time, space and resources required may not be available. As a teacher, you have to use your professional judgment to decide when a demonstration is appropriate. You need to justify that decision in terms of your students’ learning, rather than on what is easiest for you as the teacher. Not all processes and phenomena lend themselves to classroom demonstration; some may be too complicated or lengthy to be practical in the classroom environment.
For your students, demonstration has the potential advantage of being ‘better, more visible, clearer and with more impact than a class experiment’ (Wellington and Ireson, 2012, p. 165). However, it may mean that students are less actively involved, do not learn a great deal and get bored. The question is, then, how can you as the teacher maximise students’ participation, support their learning and capture their interest?
Part of the answer is making sure that you are clear about the purpose of the demonstration and know what you want it to achieve.
Demonstrations have a number of possible purposes. These can be categorised into three broad types:
- to illustrate a phenomenon, concept, law, theory or process
- to motivate and stimulate, arousing students’ curiosity prior to teaching
- to help students articulate and explore their existing ideas.
All of these are important and a single demonstration may achieve more than one. The purpose will affect how you plan and carry out the demonstration.
Case Study 1: Cooking food
Food is a topic that interests children. It is something that is part of their everyday lives and an important part of their cultural heritage. It is relatively easy to make teaching the topic of food relevant to students’ experience and future lives. Younger children might be introduced to food in the context of the home. In this case study, Mrs Rawool teaches a class of young children about the changes that happen when food is cooked.
I included a demonstration of cooking different foods – for example, rice, spinach, roti and vegetables – to get them interested and observe more closely. First, I got the students to look at the foods before they were cooked and asked them to describe them. I wrote the words they used on the blackboard. During the demonstration of the cooking, I asked the students questions to keep them focused and interested. I also let the two students who are visually impaired feel the foods. They gave some different words to describe them that I wrote on the blackboard.
This is an excerpt from my lesson:
Mrs Rawool What is the rice like before it is cooked?
The students gave descriptive words and I put the words on the blackboard. I encouraged the students to consider colour, shape and texture and used questions to get them to look at the food more closely. For example:
Mrs Rawool What colour is it?
Student White.
Mrs Rawool Is it white like this? (I pointed to a white object.)
Student No, it’s browner than that.
Mrs Rawool Good. Let’s see what happens as the rice boils. (I put rice into boiling water.) What do you think will happen?
Student It will get whiter.
Mrs Rawool How do you know?
Student Because my mother cooks rice at home.
Mrs Rawool Hands up if you like eating rice.
The students all put their hands.
Mrs Rawool Who likes to eat rice before it is cooked?
The students’ hands all go down. They laughed and made faces, suggesting that this was a silly idea.
Mrs Rawool While the rice cooks, we will look at the spinach. What is spinach like before it is cooked?
I put the spinach into a bowl and students answered the question. I put their answers on the blackboard.
Mrs Rawool Who has eaten cooked spinach? What happens when it is cooked?
The students contributed their knowledge based on their experience at home. I cooked the spinach and the students watched intently as it changed. I kept them focused on what was happening by asking questions such as:
- ‘How has the spinach changed?’
- ‘How did the rice change?’
- ‘What was it that made the food change?’
- ‘Which food changed the most?’
- ‘Why do we cook food?’
 Video: Using questioning to promote thinking |
You may find it useful to now look at Resource 1, ‘Using questioning to promote thinking’.
Pause for thought
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Why this approach is important