4B - Evaporation and Condensation Autumn 1.

Class 4B – Autumn 1 – States of Matter

Evaporation – Designing Experiments

Class 4B wanted to know what would happen when they heated water particles, so they designed a fair test to challenge their theory. They filled trays with equal amounts of salt water and then positioned them variously in direct sunlight, under a rotary fan and underneath a hot air drier. A control tray was left undisturbed to provide a comparison and ensure a fair test. The children discovered the water under the hot air drier seemed to disappear first. They discussed whether this was melting before deciding it must be evaporation because the water particles had broken free of their bonds and become a gas.

Condensation – Explaining Science

Class 4B continued their work on states of matter by addressing a concept cartoon and asking themselves why water droplets appear on the outside of a cold glass on a hot day. They explained that the glass hadn’t leaked but the water particles must have come from somewhere else. Taking a chilled mirror each, they exhaled onto the mirror and observed tiny droplets form on the surface. Class 4B concluded that this must be the ‘steam-like’ water vapour in their lungs condensing back into a liquid as the temperature changed.