Learn Index · Mathematical Thinking and Problem Solving Grade 9–10

Communicating mathematical reasoning

Using words, symbols and diagrams to explain your thinking.

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Maths is a language

Doing maths in your head is one thing. Explaining it so others understand is a separate skill. Engineers, scientists, accountants and programmers all have to communicate their reasoning clearly.

The parts of clear communication

Part What it means
Correct notation Use symbols properly.
Precise vocabulary Use the right maths words.
Logical order Steps follow from one another.
Words + symbols Explain key steps in sentences.
Visuals Diagrams, tables and graphs, labelled.
Conclusion Answer the question in a sentence with units.

Using notation correctly

Correct Incorrect Why
3 + 4 = 7, 7 × 2 = 14 3 + 4 = 7 × 2 = 14 3 + 4 doesn’t equal 7 × 2
π ≈ 3.14 π = 3.14 It’s an approximation
x = 5 5 Say what the 5 is
20 cm² 20 Include units

The equals sign must always join two things that are truly equal. Don’t use it to mean "next step".

Using precise vocabulary

Vague Precise
"the number in front of x" the coefficient
"the line goes up" the slope is positive
"the answer" the product / the solution / the sum
"the box shape" rectangular prism

Know your audience

Your audience shapes how much detail you include:

  • A teacher: show method and justify key steps.
  • A classmate: explain why, with an example.
  • A client or the public: plain language, clear conclusions and visuals.

A model solution

Problem: A rectangular garden has a perimeter of 36 m. Its length is twice its width. Find its area.

Solution:

Let w be the width in metres. Then the length is 2w.

Perimeter: 2(w + 2w) = 36

6w = 36, so w = 6.

Width = 6 m, length = 12 m.

Area = 6 × 12 = 72 m².

The garden’s area is 72 m².

Check: perimeter 2(6 + 12) = 36 ✓

Communicating with graphs and tables

  • Give every graph a title.
  • Label axes with quantities and units.
  • Choose a sensible scale.
  • Refer to visuals in your writing ("As the table shows…").

Oral communication

When explaining aloud: state the goal, walk through steps, point to visuals, and invite questions.

Worked examples

Example 1: Improve: "x is 4." → "The solution of the equation is x = 4."

Example 2: Fix: 5 + 3 = 8 ÷ 2 = 4. → "5 + 3 = 8, and 8 ÷ 2 = 4."

Example 3: Replace with precise vocabulary: "the bottom number of the fraction" → denominator.

Common mistakes

  • Run-on equals signs.
  • Missing units or labels.
  • Answers with no concluding sentence.
  • Skipping steps your audience needs.

Try it yourself

  1. What’s wrong with writing 4 × 5 = 20 + 3 = 23?
  2. Give the precise term for "the answer to a division".
  3. Write a concluding sentence: a car travels 180 km in 2.5 h; speed 72 km/h.
  4. Name two features every graph should have.

Answers: 1) 4 × 5 isn’t equal to 23. Write 4 × 5 = 20, then 20 + 3 = 23. 2) quotient 3) The car’s average speed is 72 km/h. 4) a title and labelled axes (with units)

Quick recap

  • Communicate with correct notation and precise vocabulary.
  • Organize steps logically and justify them.
  • Aim for clarity for your audience.