How to teach the water cycle

The four stages are evaporation, condensation, precipitation and collection. The Sun heats water so it evaporates into vapour, the vapour cools and condenses into clouds, the water falls as precipitation like rain or snow, and it collects in rivers, lakes and the sea before the cycle repeats.

The water cycle is usually taught from Grade 2 to Grade 5. Younger students focus on the four stages and everyday examples like puddles drying and rain falling, while older students add the role of the Sun's energy and the idea that Earth's total water stays about the same.

Evaporation is liquid water turning into invisible water vapour, a gas, when it is heated, such as a puddle drying in the sun. Condensation is the reverse: water vapour cooling back into tiny liquid droplets, such as mist forming on a cold glass. Children often mix the two directions up.

The Sun is the energy source that drives the whole cycle. Its heat causes evaporation, lifting water into the air as vapour, and the movement of air and the cooling higher up do the rest. Forgetting the Sun's role is a common gap, so it is worth stressing.

No. The water cycle is a continuous loop with no start or finish; the same water moves endlessly between the sea, the sky and the land. Thinking it begins or ends somewhere is the most common misconception, so tracing a single drop round and round the diagram helps.

No. Rain is the same water recycled, not new water. The water falling today has cycled through evaporation, clouds and rain countless times before. Earth's total amount of water stays roughly constant, which is why the process is a cycle rather than a one-way journey.

Seal some warm water in a clear jar with a lid. The water evaporates, condenses on the cool lid as droplets, and 'rains' back down, showing the whole cycle in miniature. It makes evaporation, condensation and precipitation visible in a few minutes.