Key Stage 2 geography · Human and physical geography

KS2 rivers and the water cycle: a guide for parents

In Key Stage 2, children learn that water is constantly moving between the sea, the air and the land in a continuous loop called the water cycle. They also follow a river from its source in the hills to its mouth at the sea, and learn how it shapes the land along the way. Together these ideas explain where rain comes from and where river water goes.

Rivers and the water cycle, explained

The water cycle describes how water keeps moving without being used up. The Sun warms the surface of seas, lakes and rivers, and some of the liquid water turns into an invisible gas called water vapour. This is evaporation. Plants also release water vapour through their leaves, which is transpiration. As the vapour rises, it cools and turns back into tiny droplets, forming clouds. This is condensation. When the droplets grow big and heavy enough, they fall as precipitation: rain, hail, sleet or snow. The water then runs over the ground or soaks into it, and collects in rivers, lakes, the ground and the sea, ready to start again. Many schools call this last stage collection.

A river begins at its source, often a spring or the run-off from hills where rain has fallen. A small stream joining a larger one is called a tributary, and the place where they meet is a confluence. In the upper course, near the source, the land is steep and the channel is narrow, shallow and rocky. Here the river cuts down into a V-shaped valley and can form waterfalls. In the middle course the valley widens. In the lower course the land is flat, the river is wide and deep, and it bends into curves called meanders. The river ends at its mouth, where it meets the sea, sometimes widening into an estuary.

Rivers shape the land through three processes. Erosion is the wearing away of the bed and banks. Transportation is the carrying of rock and soil downstream. Deposition is the dropping of material wherever the water slows down, such as on the inside of a bend or when a river floods and spreads out, which builds up flat land called a floodplain. Many schools show how a meander can eventually be cut off to leave an oxbow lake. Children look at a map or photographs of a real river and describe what they see at different points.

Because the topic is also about significant features of the world, children learn some famous rivers and their locations. The Nile and the Amazon are usually named as the longest in the world, with experts disagreeing about which is longer depending on how they measure the source. In the UK, the Severn is the longest river, and the Thames is the longest wholly in England. Rivers matter to people because they supply water, provide transport and fertile land, once powered mills, and sometimes cause floods.

Words your child will hear

Evaporation: Liquid water turning into water vapour, a gas, usually because the Sun has warmed it.
Condensation: Water vapour cooling and turning back into tiny drops of liquid water, forming clouds.
Precipitation: Water falling from clouds as rain, snow, sleet or hail.
Source: The place where a river begins, often a spring or small stream in high ground.
Tributary: A smaller river or stream that flows into a bigger river.
Meander: A wide bend in a river on flat land.
Mouth: The place where a river flows into the sea or a lake.

What the National Curriculum says

The programme of study for Key Stage 2 says:

Pupils should be taught to describe and understand key aspects of physical geography, including: climate zones, biomes and vegetation belts, rivers, mountains, volcanoes and earthquakes, and the water cycle
This will include the location and characteristics of a range of the world’s most significant human and physical features.

Objectives from the National Curriculum in England, © Crown copyright, used under the Open Government Licence v3.0.

Try it: following a raindrop

A raindrop lands on a hill. Describe its journey until it is rain again.

Precipitation. Moist air rises over the hill, cools, and the droplets in the cloud join together until they fall as rain. The raindrop lands on the grass.
Run-off and source. Some of the water soaks into the soil, but on a steep, wet hill most flows downhill over the surface into a small stream. This is the river’s source. It joins other streams, which are its tributaries.
Upper to lower course. The stream tumbles over rocks, eroding the valley and carrying stones. Further on, the land flattens, the river widens and winds in meanders, and it drops some of the sediment it carries where the water slows, such as on the inside of bends. This is deposition.
Mouth. At the mouth, the river flows into the sea through an estuary and the freshwater mixes with salty seawater.
Evaporation and condensation. The Sun warms the sea surface and some water evaporates as vapour, leaving the salt behind. The vapour rises, cools and condenses into cloud, and the wind carries it over land to fall again as rain.

The raindrop falls as precipitation, runs downhill into a stream and along a river through its upper, middle and lower courses, and reaches the sea at the mouth. There the Sun evaporates some water, which condenses into clouds and falls as rain again: the water cycle.

Common mistakes and how to help

Thinking clouds are made of steam or smoke, or that rain falls out of holes in the clouds

Clouds look solid, and they sit in the sky in a way that is easy to compare with smoke or cotton wool.

What helps: Show a mirror breathed on, or a cold glass of water, and talk about how the vapour in the air turns to tiny drops. Clouds are millions of such tiny drops.

Believing water has to boil to evaporate

Children associate steam with a kettle, so they link vapour with heat only.

What helps: Put a puddle or a damp cloth outside on a dry day and watch it vanish. Evaporation happens at any temperature, just faster in the warm.

Thinking rivers always flow north to south, or can flow uphill

Many maps show rivers running down the page, and children may pick up the idea that “down” means south.

What helps: Find several rivers on a map and follow their direction. Rivers always flow downhill from the source to the mouth, whatever direction that happens to be.

Thinking rain is salty because it comes from the sea, or that salt evaporates with the water

Children assume everything dissolved in the water is lifted up with it.

What helps: Dissolve salt in warm water and leave a saucer of it on a windowsill. The water disappears over a few days and the salt stays behind, which is why rain is fresh water.

How to help at home

A mini water cycle. Pour a little warm water into a clear plastic bag, seal it, and tape it to a sunny window. Watch drops form higher up on the inside and trickle back down.
Puddle watching. After rain, draw round the edge of a puddle with chalk and check back every hour. Ask where the water has gone, and why it dries faster on a warm, windy day.
Follow the water in your street. Notice where rain runs on your street after a shower: drains, gutters and slopes. Ask your child where they think it ends up, then find the nearest stream or river on a map.
Read a river on a map. Pick a river, find its source and mouth on an atlas, and name any towns and tributaries between them. If you visit a river, stay with an adult well back from the edge, and look for the width and speed of the water.

Builds on

Key Stage 1: Weather and seasons
Key Stage 1: Hot and cold places
Key Stage 1: Coasts, seas and oceans
Key Stage 1: Hills, rivers, forests and soil
Key Stage 1: Towns, villages, farms and ports

Leads on to

Key Stage 3: Plate tectonics and geological time
Key Stage 3: Rocks, weathering and soils
Key Stage 3: Weather and climate
Key Stage 3: Climate change from the Ice Age
Key Stage 3: Glaciation and glacial landforms
Key Stage 3: Rivers and drainage basins
Key Stage 3: Coastal processes and landforms
Key Stage 3: Population
Key Stage 3: Urbanisation and the growth of cities
Key Stage 3: International development
Key Stage 3: The four sectors of economic activity
Key Stage 3: The use of natural resources
Key Stage 3: How people change landscapes and climate
Key Stage 3: How people depend on natural systems