Weather Forecasting
Weather Forecasting is using simple tools like a homemade barometer to predict what the sky will do next.
Think of it this way
A sealed jar half-filled with water sits on the counter. When air pressure drops, the water level inside rises. When pressure builds up, the water level falls back down. Rising water warns of rain, and falling water means clear skies ahead.
Explaining weather forecasting by grade level
You can build a barometer from a coffee can. It shows when air pushes more or less. When the air push changes, the weather changes too. That is how you guess what comes next.