Working with Negative Numbers

Students learn how to use written methods to order and calculate with negative numbers.  Learning progress from performing arithmetic on a number line to multiplying and dividing with negatives.

This topic takes place in Term 2 of Year 9 and follows Properties of Numbers.


Working with Negative Numbers Lessons
Problem Solving and Revision Lessons

Prerequisite Knowledge

  • count backwards through zero to include negative numbers
  • interpret negative numbers in context, count forwards and backwards with positive and negative whole numbers, including through zero
  • use negative numbers in context, and calculate intervals across zero

Success Criteria

  • order positive and negative integers
  • apply the four operations, including formal written methods, to integers, both positive and negative

Key Concepts

  • To order negative and positive numbers temperatures can be placed along a thermometer.
  • Use a number line to demonstrate how negative number is less than its positive counterpart but of equal magnitude.
  • Use a number line to demonstrate addition and subtraction involving negative and positive numbers.
  • Adding a negative is equivalent to a subtraction. ( 4 + -2 = 4 – 2)
  • Understanding why subtracting a negative results in an addition is vital to multiplying and dividing with negative numbers.

Common Misconceptions

  • Students often incorrectly consider negative numbers with a larger magnitude than positives to have a greater value. For example, -3 < 2.
  • Common incorrect answers to -4 + 6 are -2 (4 – 6) and -10 (-4 – 6)
  • Trying to remember multiplication rules for when to leave the answer as a positive or negative often results in confusion when adding and subtracting. Use a number line to demonstrate -3 x 2 = -3 + -3 = 6.

Go ad-free and get access to over 500 lessons

Mr Mathematics Blog

Two-Way Tables and Frequency Trees

Problem solving lesson on two-way tables and frequency trees.

Plotting Curved Graphs

Three typical exam questions to revise on plotting quadratic, cubic and reciprocal graphs.

Interpreting Cumulative Frequency Graphs

Linking cumulative frequency graphs to ratio, percentages and financial mathematics.