Get a string line and bang two pegs in the ground 3 metres apart. Get some help and another tape measure and you measure 4m from your peg and your "assistant should measure 5 m from their peg. Move toward each other and the point where your 4m meets their 5m bang in a peg. You have just created a right angled triangle and as a result of that you have 2 sides of your square. Now you move to the last peg banged in and measure out 3m your assistant should measure out 4m from their original peg. Bang the peg in where these two measurements meet and you then have a perfect rectangle 4m x 3m. From this rectangle, or even just two of its sides, you can get a perfect square. This formula is called the 3 4 5 method and works in any units, eg feet and inches. If one side is 3 long, another 4 long, the third side of the triangle, or hypotenuse will be 5 units long. For further information this is called Pythagoras Theorum and you can see it at work in our laying floorboards project.