**Comparison and ordering**

The foundation of all aspects of measurement is direct comparison, putting two and then more than two objects (or events) in order according to the attribute in question. The language of comparison is of central importance here.

**Teaching Point**

*Always introduce new aspects of measurement through direct comparison and activities involving ordering.*

Recording the results of comparison and ordering can be an opportunity to introduce the *inequality signs* (< and >). So, for example, ‘A is longer than B’ can be recorded as A > B, and ‘B is shorter that A’ as B < A. This introduces in a practical context an important principle of inequalities that can be expressed formally as follows:

If A < B, then B > A.