From seeing to thinking
Yasmin Jayathirtha
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.
Ask the students to explain the observations, you will find that they will get the theory fairly correctly, though in rather informal language. You can then give the more formal language of the kinetic-molecular theory. I have found that many topics can lend themselves to this method.
Over the next few months, I would like to explore and share how to teach chemistry through experiments. A large part of the problem with lab work is the need to have a lab! And chemicals! There are many types of chemistry teachers – those who have well-equipped labs with glassware, sinks, gas connections and a budget for chemicals, those who just have a space with a limited budget and very many who may not have a dedicated space at all. Then there are home schoolers. All of these need to teach chemistry so that the students can get certified. How can one design lab work that can be undertaken by all? This is where we have to break away from how we have learnt in our schools and colleges and ask what is the core of the theory we’re trying to teach. For example, trying to teach titrations. Burettes and pipettes are expensive, so we feel we may just have to show them pictures. But the core of those experiments is to determine concentrations through quantitative reactions. We can use syringes (available very cheaply) and students can do the experiments and the calculations required. Small-scale chemistry, using drops of solutions and using chemicals commonly available can save money and make it easy to control in large classrooms. I would like to build up an experimental version of a standard certificate course in chemistry covering all the topics. At all points I would like to share various options available and how to substitute or improvise. I hope this will help teachers think about how to set up experiments and that students will learn how to infer and use data.
The author works with Centre for Learning, Bengaluru. She can be reached at yasmin.cfl@gmail.com.