Then she talked about what happens when a cold front meets a warm front. She had two of us pretend we were fronts, and showed what happened when we "collided" into each other!
She taught us about air (or barometric) pressure, which is the pressure of the atmosphere against the Earth's surface. Gravity makes this happen!
Cloudy or rainy weather can be expected when we're in an area of "low barometric pressure". An air mass with "high barometric pressure" brings fair weather!
We listened carefully to her instructions on making our own barometers, which measure air pressure.