Overview

This part summarizes key properties and conventions of the number line.

It is important for teachers to have explicit understanding of the properties and conventions of representations, even though they may not discuss them directly with students. Such understanding helps teachers more skillfully use the representation with students, and enables teachers to share or elicit selected ideas with students at strategic times.

Key Points

• Properties and conventions of the number line:
  • locating numbers
  • two infinite directions
  • increase to the right
  • positive and negative
  • unit interval
  • labeling points
  • symmetry
• Other observations about the number line:
  • There are infinitely many equivalent forms of a number.
  • The number line represents the real numbers.
  • The rational numbers are dense on the line.
  • A number and its additive inverse are the same distance from 0.
  • A mathematical object.