**You need to tell someone
how to get from one place to another. Sounds easy enough and if you were at the
bottom of the street where you live and, you were directing someone to the
nearest public telephone you could probably do a pretty good job without a map.**

**But imagine you've just
been left in the middle of a field and given a piece of paper, a compass and a
collection of maps. On the paper is written the following;**

**(Start) TQ083305**

**(Finish) TR127336**

**Off you go then, dinners at
eight! However, if your not too sure about what the letters and numbers mean
read on and I'll try to explain. Ordnance Survey maps are all about squares and
tens, if you remember that your well on your way.**

The big Squares

**Take a
very big photograph of the British Isles (or anywhere else for that matter) and
cut it up into big squares. To identify all those squares you could give each one a
name like Fred, Jim, Peter etc. but that would be too much fun! So instead you
give each of them some letters. **

**So the letters at the
beginning of all those numbers tell you which map to look at. Each map will have identification letters at the bottom of it near to where the symbols are
explained, and some have them on the corners of the map as well. Take a look at an Ordnance
Survey map and see if you can find them.**

**Now you have found the
right map you need to find out where you are and where you are going to.**

The small squares

**Each map is divided into
smaller squares by lines drawn from top to bottom, left to right. These lines
are called grids.**

**If you look around the
edges of our map (below) you will see that each line from top to bottom has a
two digit number and so does each left to right line. These are
called grid reference numbers, they also appear on Ordnance Survey maps.**

**To help you, the large
numbers on our map are coloured RED
and BLUE.
**

**It is important to remember
that you always read the top or bottom
(RED) number first followed by
the
left or right (BLUE) number.**

**Take a look at our map and
see if you can find where the lines meet at this grid reference ;
3344.
**

**....Continued below
map↓**

**If you got that right you
now have the basics. But the Grid Reference you have just found will only get
you within a kilometre or so. To get closer you need some more detailed
information.**

The really small squares

**This is done by dividing
each square up into smaller squares. The problem is, these small squares are
not shown on real maps, you have to "imagine" them.**

**The map
above has one of it's grid squares divided by the extra lines and they are
numbered to show you how to do it. You
might notice that these numbers are coloured black or mauve.**

**Can you also see how the
squares are divided and numbered? **

**From left to right.**

**31
1,2,3,4,5,6,7,8,9
32
1,2,3,4,5,6,7,8,9 33
1,2,3,4,5,6,7,8,9 34
1,2,3,4,5,6,7,8,9
**

**From bottom to top**

**44
1,2,3,4,5,6,7,8,9 45
1,2,3,4,5,6,7,8,9 46
1,2,3,4,5,6,7,8,9**

**Try finding the yellow
cross on our map at this grid reference 322452.
**

**Can you see how important
it is to use the top bottom numbers first then the left right numbers? If you
get them in the wrong order you could end up somewhere else!**

**See if you can find the
exact Grid Reference of the GREEN CROSS on our
map, it should have six numbers and don't forget to
read the top or bottom number BEFORE the left or right number. (click
here to check your answer).**

**It may be helpful if you had an
Ordnance Survey map to refer to**

**A grid reference normally consists
of a six digit number like 337529. There may be letters at the beginning these
numbers like TR337529.**

**To read the grid reference you must
first of all break it down into sections.**

**If shown, the letters (TR) refer to
the map that should be used. Each "OS" map has it's ID letters printed at the
bottom by the symbol key.**

**Next, divide the six remaining
numbers into two groups of three, 337 and 529.**

**The "33" refers to the numbers at
the top and bottom of the vertical lines on an OS map and the 7 refers to a
point towards the line to the right (34). If the third number was a 5 this would
be half way between 33 and 34, got the idea? **

**The "52" refers to the numbers left
and right of the horizontal lines and the 9 refers to a point towards the line
above (53). If the third number was a 5 this would be half way between 52 and
53.**

**323456**

**click
here to go back to where you were**