Key Stage 3 geography · Geographical skills and fieldwork

KS3 geography: using GIS to map and analyse data

A Geographical Information System, or GIS, is software that stores information about places as a stack of digital map layers, so that pupils can switch layers on and off, compare them and ask questions of the data. The National Curriculum asks KS3 pupils to use GIS to view, analyse and interpret places and data, and to get better at judging what different data sources can and can’t tell them. It builds on the digital mapping children met in primary school, and it is where map skills turn into real enquiry.

Geographical Information Systems (GIS), explained

Think of a GIS as a pile of see-through maps. One layer might show rivers, another roads, another where people live, another the land that floods. Each layer holds data that is tied to a real position on the Earth’s surface, so the layers line up exactly. Pupils can look at one layer alone, or switch several on at once and see where they overlap. A paper map shows you one picture the mapmaker has already chosen. A GIS lets your child decide which pictures to combine.

Layers are built from a few kinds of data. Vector data uses points (a school, a weather station), lines (a road, a river) and polygons (a flood zone, a council ward). Raster data is a grid of cells, like the pixels in a photograph, and is how satellite images and height or rainfall surfaces are stored. Behind every point, line or polygon sits an attribute table: a spreadsheet with a row for each feature and columns such as name, population or year. Clicking a feature on the map shows its row, which is how pupils move from “where is it?” to “what is it like?”.

KS3 pupils use GIS for three jobs, matching the wording of the curriculum. They view: finding a place, zooming in and out, and changing the background between a map and an aerial image. They analyse: sorting or filtering the table (for example, only wards where more than a quarter of people are over 65), measuring distances, drawing a buffer zone of, say, 500 metres around a feature, and overlaying layers to find places that meet several conditions. They interpret: deciding what the pattern means, suggesting reasons, and judging how reliable it is. Schools choose their own software, from free online tools to professional packages, and the skills carry across.

Interpreting is where geography, rather than button-pressing, happens. Pupils ask who collected the data and when, whether it covers every place equally, and how the way it was classified changes the picture. A colour-shaded map of rates or percentages (a choropleth map) can look very different if the categories are changed. A map showing only the number of cases will mostly show where the people are, whereas a map of cases per 1,000 people shows something else. Pupils may also test a mapped pattern against a geographical model, for example comparing real land use in a town with a model of how land use changes from the centre outwards, and explain where the town fits and where it doesn’t. This is the “greater competence” in using concepts and analysing different data sources that the curriculum asks for at KS3.

Words your child will hear

Layer: One set of map data, such as roads or rivers, that can be switched on or off and stacked with others.
Overlay: Placing two or more layers on top of each other to see where features coincide.
Attribute table: The spreadsheet of facts behind a layer, with one row for each point, line or polygon.
Vector and raster: Vector data is points, lines and polygons; raster data is a grid of cells, as in a satellite image.
Buffer: A zone drawn at a set distance around a feature, such as 400 metres around a station.
Choropleth map: A map where areas are shaded in different colours according to a value, such as population density.
Data source: Where information comes from, such as a census or a satellite, and how reliable it is.

What the National Curriculum says

The programme of study for Key Stage 3 says:

Pupils should be taught to use Geographical Information Systems (GIS) to view, analyse and interpret places and data
Pupils should develop greater competence in using geographical knowledge, approaches and concepts [such as models and theories] and geographical skills in analysing and interpreting different data sources.

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

Try it: choosing a site with map layers

A town wants a new health centre. Using a GIS, how would you decide which of three possible sites (A, B and C) is best? The layer details below are made up to show the method.

Set the criteria first. The town agrees the health centre should be outside the flood zone, within 400 m of a bus route, and close to where many older people live. Without clear criteria, a map is only a pretty picture.
Switch on the flood-zone layer. Site B sits inside the flood zone, so it fails the first test. Sites A and C remain.
Create a 400 m buffer around the bus-route layer. Site A is 150 m from a route and inside the buffer. Site C is 700 m away and outside it.
Add a shaded layer showing the percentage of residents aged 65 or over in each ward. Site A is in a ward where 31% are 65 or over, and the borough average is 19%.
Check the limits of the data. The age layer is from a census taken some years ago, and the bus layer says nothing about how often buses run. Note these before making a final recommendation.

Site A is the best choice because it is outside the flood zone, inside the bus buffer and in a ward with a high share of older residents. The recommendation is cautious: the census data may be out of date and bus frequency was not mapped, so a visit and some newer data would strengthen the case.

Common mistakes and how to help

Thinking a GIS is just a clever online map

Most children first meet digital maps through navigation or satellite views, which show one picture. The analysis side, such as filtering, buffers and overlays, isn’t visible in everyday use.

What helps: Ask a question that one layer can’t answer, such as “which streets are both near a park and far from a main road?”, and talk through which layers you would need.

Believing that a pattern on a map proves a cause

When two layers overlap, it is tempting to say one caused the other. Two things can sit in the same place for many reasons, including that both simply follow where people live.

What helps: Use the words “is linked to” or “might be because”, and ask what else could explain it. A good conclusion gives evidence, a possible reason and a doubt.

Treating colours and category boundaries as neutral facts

A choropleth map looks authoritative. Pupils often don’t realise that choosing different class boundaries, or showing totals instead of rates, can change which areas look worst.

What helps: Look at the same data shown two ways and spot the differences. Ask whether the map shows numbers or numbers per person, and why that matters.

Assuming digital data is always accurate and up to date

Layers look precise and are drawn to the metre, which makes them seem trustworthy. Many are built from surveys or samples that are years old or miss some places.

What helps: Make it a routine to ask “Who made this, when, and who or what might be missing?” before using any data map as evidence.

How to help at home

Build a layered map on paper. Draw your street area on a sheet of paper, then trace separate layers on baking paper: homes, shops, green spaces, roads. Stack them in different combinations and talk about what each pairing shows.
Compare map view and aerial view. Together, open a free web map of your area on a phone or computer and flip between the map and the aerial image. What can you see in one that is hidden in the other, such as tree cover, car parks or building shapes?
Plan something with criteria. Choose a family outing or picnic spot using three rules, for example near a bus stop, near a play area and away from a busy road. Using a map, find the places that meet all three and say why the others fail.
Question a data map in the news. When a shaded map of rainfall, health or population appears in a news story, ask together what the colours show, whether it is a total or a rate, and what the map can’t tell you.

Builds on

Key Stage 2: Atlases, globes and digital maps
Key Stage 2: Compass points and grid references
Key Stage 2: Ordnance Survey map symbols
Key Stage 2: Fieldwork: observe and measure
Key Stage 2: Fieldwork: presenting findings