Ordering directed numbers on the number line

2026-11-02Numbers & Estimation Mr Chan

Compare and arrange positive and negative integers for S2 foundation checks.

Key formulas

a < b \text{on the number line means} a \text{is left of} b

What this lesson covers

This lesson builds Secondary 2–3 skill in number line order. Read the key formulas, study the worked example, then attempt the written practice and the four-question MCQ review.

Method

Write every step. Name the rule you use (number line order) before substituting numbers. Keep units and signs visible until the final sentence.

Common mistakes

Students often rush the sign, use the wrong percentage base, or cancel terms instead of factors. Pause after each line and ask whether the step is reversible.

Exam habit

Underline the question verb (simplify, solve, factorise, find). Box the final answer and, where sensible, substitute back for a quick check.

Worked example

Worked example — number line order

Problem. Apply the method for number line order with the numbers 4 and 3.

Solution. Identify the rule for number line order. Substitute 4 and 3 carefully with signs in brackets if needed. Complete each operation on a new line. State the final answer clearly and check by reversing one step.

Review quiz

1 / 4

Warm-up on number line order: what is 3+2?

Practice questions

Practice 1 on number line order: compute with the value 10.
Practice 2 on number line order: change the numbers and repeat the same method.
Practice 3 on number line order: write one sentence explaining the key rule.
Practice 4 on number line order: invent a similar exam-style question and solve it.

Study notes

What is the main idea of number line order?

Apply the stated formula or rule with clear steps, then check by reversing or substituting.

How should I revise this topic?

Cover the worked example, redo the practice without notes, then complete the MCQ set and log any wrong options.