You can use rods of lengths 3, 4 and 6 units to measure different lengths.

The diagrams shows how to measure lengths of 1, 3, 5 and 7.

**Can you see how to measure a length of 2?**

There are rods for 4 and 6, so it's possible to measure all the lengths from 1 to 7.

**Can you convince yourself you cannot measure a length of 8?**

**Can you find another set of three rods that can be used to measure all the lengths from 1 to 7? **

**What about 1 to 8? **

**1 to 9? **

**1 to ...?**

*How far can you go? Take a look at Longer and Longer to explore further.*