Perimeter

Objective. Calculate and solve problems involving the boundary of shapes.

1. Learn
2. Worked example
3. Practice
4. Feedback
5. Continue

Learn: the key idea

Perimeter is built on a small number of dependable facts. Classify shapes and calculate measures with correct units. Represent the information first, choose a method deliberately, show each step and use an inverse operation or estimate to check that the result fits the question.

Worked example

Find the perimeter of a 6 cm by 5 cm rectangle.

1 $Identify the mathematical information and what must be found.$
2 $Represent it with a number line, diagram, table or expression where helpful.$
3 $Apply the relevant fact carefully and keep each line clear.$
4 $Check the result against the conditions in the question: 22 cm.$

Answer: 22 cm

Concept mastery

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Practice

Practice happens on its own screen, one question at a time. Answers stay hidden until you submit yours, and you can stop and pick up at the same question later.

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Common mistake. A common mistake in perimeter is to apply a remembered procedure before reading the signs, units or order carefully. Write the structure first, then calculate and check.

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