Science is one of my favourite tools for explaining how the world works because I find it fascinating. It takes abstract things and puts them into meaningful information that I can understand. The interaction of matter is my favourite because the outcome is set and predictable.
If you leave a block of ice out in the sun, you’ll notice that it will melt and eventually become a puddle of water. The reverse applies to putting water in a freezer. This is called a change of state.
Heating
When you apply heat to something that melts, like a chocolate egg for example, the molecules inside the chocolate will begin to vibrate. As their energy increases, thus causing the substance to melt, a solid is transformed into a liquid state. 
Liquids
When a liquid takes up the volume inside a glass, the particles are moving about, filling the container. If more heat is applied to the liquid, it will boil and bubble, and produce a gas. Gases are another state of matter where there is so much energy, that the liquid boils off, evaporates and turns into its gas form which spreads out and does not have a definite volume.
Cooling
When we cool down a gas, the number of particles increase, and the gas returns to a liquid state. The reason gases spread out and do not fill a volume is because the particles have a lot of energy, so they break free of their molecular bonds. Try opening a jar of steam, and the steam will rush out. This is a gas.
Warning!
Be very careful when handling hot liquids and gases – they can burn you. 
Hot gases contain much more thermal energy than a liquid does, so be extra careful around these.
Condensation and the Water Cycle
When steam from a bathtub or shower hits the cold tiles of a bathroom, it changes from a gas to a liquid state very rapidly.
This is called condensation, and is the opposite of evaporation.? This is the same reason Earth has clouds. Evaporation of water rises and cools, creating clouds where the particles then collide together and get bigger and bigger until they fall to the ground. This is known as rain. 
