Natural water sources on Earth
Water is found in many places on Earth. A river flows in a channel and a lake is water collected in a hollow. Seas and oceans are huge and their water is salty, so it cannot be drunk. Rain and snow are also water sources: they fill rivers and lakes. Rain and snowmelt seep into the ground and collect underground: this is groundwater. Where it comes out onto the surface is a spring. People get groundwater by digging wells. We must keep water clean: do not throw rubbish in water, do not wash cars by water bodies, and clean used water.
Model “Water cleaning”: in the neck of a cut plastic bottle put cotton, then sand, then small stones. Place a glass underneath. Carefully pour in muddy water (water + soil). After passing through, the water is clearer but still not drinkable: treatment plants also remove germs. Safety: an adult cuts the bottle; never drink filtered water.