This article, written for students, looks at how some measuring units and devices were developed.

Can you put these shapes in order of size? Start with the smallest.

I cut this square into two different shapes. What can you say about the relationship between them?

Hand Span

2hands

Spread your fingers as wide as you can,

What you have now is called a hand span .

A hand span can help you to find out how big

Is the height of a cow, a horse or a pig.

Use your hand span very carefully and see

How many it takes to go right round a tree.

Now get a good friend and make this a game,

Compare if the number of spans round the tree is the same.

Next find an adult and compare their hand span too

To see if they use more or less spans than you.

Now write down the answers and think as hard as can be,

Why is it better to use a tape measure like me?

Tape measure.