States of matter

Matter exists in 3 states… actually, 4 – Solids, Liquids, Gases and Plasma. To keep things simple I taught the kids that only three states of matter exist.

Then we started classifying the things around us under solids and liquids and gases. When it came to gases, i was surprised by the examples they gave. They seem to know Oxygen, Helium, Hydrogen and even Carbon dioxide. But they were unaware of a gas which is around us – The Air.
Kids gave a puzzled look when I said that the Air around us is a gas which contains Oxygen, Helium, Hydrogen and Carbon dioxide.

To understand the difference between the three states at the molecular level, we did a small activity.

I cut a paper into tiny bits and used those small bits as molecules.

Molecules are packed tightly in solids and are strongly bonded giving rise to rigidity in solids . So kids pasted those tiny paper bits close to each other.

Molecules are packed relatively lose in liquid and are loosely bound to each other enabling the liquids to flow freely. They take the shape of the container. Kids pasted the paper bits a little away from each other.

Gas molecules move independent of each other and are not bound to each other. They occupy the entire volume of the container. So kids pasted the paper bits far away from each other.

This activity was fun. five little chatterboxes were glued to their sheets.. 15 mins of peace and silence.

To show them change from one state to the other, I took out few ice cubes from the freezer and put them in their hands. The solid ice partially melted to form liquid water. Then we transferred the blocks to a container and heated it on a stove. The blocks melted completely due to the heat. Then tiny bubbles appeared at the bottom and started raising to the surface. Soon the water started boiling. The liquid water turned into water vapour also known as steam. Now I put a cold plate in the path of the steam to find tiny water droplets condensing on the plate. As more and more steam began condensing, the water droplets grew heavy and started falling down.

“Ah! This is how rain occurs”, a kid recalled what he had learnt in school. Yes this is a water cycle! The sun heats the water from several water bodies. As the water vapour reaches higher altitudes to condense and form clouds. When it becomes too heavy for the clouds to hold, the water pours down as rain or snow.