Åk 6–9
2.1 The Concept of Length

Longest and Shortest

Here you see three pencils.  Can you determine which of them is the longest and which is the shortest?

If we place them next to each other it becomes easier.

Here we see that the yellow pencil in the middle is the longest.  The blue to the right is shorter than the yellow in the middle and longer than the green pen to the left.

Your Own Units
Before it was decided that we would measure distance with the metric system, there were a number of different measuring units.  In the history section, you may have read that we used feet and arms and so forth.

If you were to describe the distance for example length your desk is, you can do this by using your own units.

For example, you could use a remote control as a unit.  Then you would be able to determine the length of the table by using the remote control.  The remote control can be abbreviated rc.

How man remote controls are your desk?

Foto: Fredrik Enander

Maybe it is 6 remote controls long, 6 rc.

As you sure can understand, this would be a difficult and tiresome if everyone had their own units when they express length.  Because of this Europe and most of the world has agreed on the common measure of length: 1 meter.  You can read about this in the next section.