The Greeks have a word called ‘hubris’ which means excessive/foolish pride or self-confidence. I certainly suffered from it when I thought it would be easy to design activities and outlines to teach atomic structure/bonding and equations to students in classes 6 and 7. I do not do it, starting from the 8th/9th, but State syllabi, wanting to put in some chemistry in the science textbooks start with it. As I began to consider what would be the best way to start, I got a messy diagram, because the concepts branch off, merge and demand a level of abstraction that younger students might find difficult. Then any learning becomes a matter of rote and pictures that other people draw become a reality for the students and they do not tend to figure out why these models work. But even established scientists did not believe in the models of atoms for a long time so it is a difficult idea to visualize.
The lesson plan or order of topics began to look more like a difficult maze than a plan;
Starting with atoms, what led to the idea of atoms i.e., the particular nature of matter? What are the activities that can give an idea that there are particles and give some idea of the sizes. This is important because we are talking about deducing the existence of things we cannot see. It can be pointed out that through instruments we can now manipulate atoms.
Over the next few columns I will share activities that can be done fairly simply to illustrate the concepts that need to be understood beyond being merely descriptive.
The existence of matter as particles
There is a story told about the coming of the Parsis to India. They came to Gujarat and asked the ruler if they could settle in his kingdom. The ruler offered them a brimming glass of milk to show that there was no space for them. The leader of the Parsis carefully dissolved a spoonful of sugar in the milk to show that they would assimilate and contribute. But mixing cannot occur if matter is continuous! Let us assume that matter is made up of particles – how do we know it’s true and how can we estimate the sizes? A lot of the experiments depend on phenomena that we know (like sugar dissolving) and thinking about it. One phenomenon is that of diffusion, both in liquids and in gases. In fact, the existence of the different states of matter is simply explained by particles.
The author works with Centre for Learning, Bengaluru. She can be reached at firstname.lastname@example.org.