Recently with my Year 10 class, we had already covered the work required for the day and so I opened the floor for general questions and discussions. It had been raining, was currently cool and cloudy, and this is how the lesson panned out.

“Sir, what’s Celsius?”
An innocent question that opened up a whole world of science… and so began the class discussion on the use of Celsius and its differences and similarities to Kelvin and Fahrenheit as units of measure of heat energy.

But the conversation did not end there. Below is a map of where the questions led:

Why we use Celsius → Freezing temperature of water vs absolute zero → Different temperature scales → Heat vs temperature → Particle Theory and Kinetic Theory → Types of Energy → Why water evaporates → States of matter → How clouds form → Where water evaporates from → Make‑up of the human body → Why we sweat → Specific Heat Capacity of Water → Density → Condensation and rainfall → Gravity → The philosophical concept of “down” → Shape of the Earth → Centrifugal vs centripetal force → Earth’s axial tilt → Seasons → Earth’s orbit → Structure of the Earth → Earth’s magnetic field → Auroras → Space exploration → Weightlessness → Mass vs weight → Living off Earth → International Space Station → Visiting other planets → Human lifespan → Global warming → Greenhouse gases → Industrial Revolution → Renewable vs non‑renewable energy → Rising water levels → Environmental impact → Living in Antarctica → Scientific research → Antarctic discoveries → Buried forests → Plate tectonics → Fossil evidence → Evolution of species…
…and that’s when the bell rang.

One of the better lessons we had run for some time. I love answering questions and seeing where the discussion leads.