Heating and cooling

Melt it, freeze it, cook it!

Solids and liquids

Ice is a solid. It keeps its shape. Water is a liquid. It flows and fills its container.

Water can be a solid (ice), a liquid (water) or a gas (water vapour).

When we heat ice, it melts into water. Chocolate and candle wax melt too.

Ice melts at 0 °C. In a hot room it melts quickly.

When we cool water a lot, it freezes into ice. Melting and freezing can go back and forth.

Water freezes into ice when it is cooled to 0 °C, like in a freezer.

Some changes cannot go back. A cooked egg cannot become raw again. Cooked rice cannot become hard rice grains again.

Heating the egg changes it for ever. Burning wood and baking a cake are also changes that cannot go back.