Why is this relevant? How is it used?
Area and grid references uses the vertical and horizontal lines on a map (called northings and eastings) to provide accurate references for where a particular feature or location is on a map. In this way, you can direct someone to the lake at a particular grid reference, or a bridge at a particular area reference. Without these references, it would be very difficult to refer to locations on a map, and to communicate with others about the features and locations on the landscapes.
Discussion
Area and Grid References use the numbers listed on the northings and eastings as a way of refering to particular grid boxes (Area references) and to locations within partcular grid boxes (Grid References).
Area References
An area reference is a way of referring to a particular grid box. Of course, any grid box has four corners – so which do we use as the unique area reference for a particular grid box? The answer is that we all agree to use the bottom left hand corner as the eastings and northings that identify a particular grid reference.
So, the area reference has four numbers, being two digits for the easting, and two digits for the northing at the bottom left hand corner of the grid square.
A grid reference therefore looks like any of the following
1243
3345
8743
Grid references
Whereas a area reference identifies a particular grid square on a map by listing the numbers for the easting and northing that meet at the bottom left hand corner of the grid square, a grid reference is much more precice – and helps us understand where within the grid square the particular object is located.
Because the grid reference is more specific, it has more numbers – it uses six numbers by comparison to the four numbers used for the area reference. The extra detail is created by dividing the vertical and horizontal edges of the grid square into tens – imagining that there are ten vertical lines within the grid square, and ten horizontal lines within the grid square.
In this way, if the item is located in the middle of the grid square (and the are reference is 1232) then the grid reference would be:
125325
The first two digits is the easting, and the third digit is a number between 0 and 9 which indicates at what tenth along the point is. Similarly, the fourth and fifth digits are the northing, with the sixth digit identifying at what tenth along the northing the point is located.
An easy way to remember that area references have four digits, and grid references have six digits, is that the A in Area comes before the G in Grid and therefore has less digits in the reference.
Common errors
Common errors with area and grid references are:
- mainly mixing them up, and forgetting that area (with A before G) has only four digits.
- not remembering that the lower left hand corner of the grid square is used for the numbers in the references
- not remembering that the eastings number is first (which is the horizontal like – like an x axis in maths) and then the northings number.
How is this tested or examined?
Area a grid references are typically examined with multiple choice of short answer questions where a map is provided which contains a legend of multiple points of interest. Students will then be asked for the area reference of a particular item (ie provide the area reference for the church), or a grid reference for a particular item (provide the grid reference for the lake). This requires the application of the skill to read the legend, identify the item in the map, and then apply the skill for area reference (four numbers) or grid reference (six numbers).
Further resources
Video on area and map references
Reading a map: great BBC resource
mygeoskills 