During the years I was writing ‘Let’s Experiment’ I was experimenting in my own classrooms, trying to find the best way to integrate experiments into the teaching of the subject. It is very clear to me that no meaningful learning of chemistry can happen without work in the laboratory. But the question is; should the experiments be illustrative of theory (like a demonstration) or should it provide data to understand and underpin the theory?
The two approaches may not sound very different from each other, both essentially doing the same experiments. But in the first, the theory is taught and the experiments make it easy to visualize it. In the second, the experiments lead to the theory. As an example, consider the teaching of the activity series. In the first approach, we would talk about metal activity series and then demonstrate it through displacement reactions. In the second approach, do the displacement reactions and then consider what information, i.e., the activity series, can be inferred from it. I would not call it experimentation, since it is not, but it opens the way to experimentation through speculation; what if the iron was replaced with another metal?
Lately, I have begun to explore the second way to teach chemistry, giving a very brief introduction to the topic, no more than a statement about what we are trying to learn about. This is followed by a series of experiments, followed by discussions linking it to the theory. To give an example, to teach rates of reactions (kinetics), the lesson can proceed as follows:
1. Make the statement that for a reaction to happen, particles of the reactants have to meet.
2. What will make the particles collide more/less often, i.e., have an effect on the rate?
3. How will we know that the reaction is occurring, what will we see?
4. Set up the experiments and observe.
The author works with Centre for Learning, Bengaluru. She can be reached at firstname.lastname@example.org.