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Grade 4 · Math · Unit 12 of 12

Angles & Area

Acute, right, obtuse and area

What your child practises

Sorting angles into acute, right, obtuse and straight, finding area by multiplying length by width, and working backward to find a side.

Nunavut Curriculum approved guide: Alberta Mathematics K–9 (2007), Shape and Space · area of regular and irregular 2-D shapes

How we explain it

Children can open this short lesson before they practise.

  1. Area is the space inside. Length × width for a rectangle.
  2. A right angle is a square corner (90°). Acute is smaller. Obtuse is bigger.
  3. Area is measured in square units, like cm².

Example: A rectangle is 4 cm long and 3 cm wide. What is its area? Multiply length by width. 4 × 3 = 12. Answer: 12 square cm

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    A rectangle is 11 cm long and 3 cm wide. What is its area in square centimetres?

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  2. Question 2

    A rectangle has an area of 72 square centimetres. It is 12 cm long. How wide is it, in centimetres?

    12 × = 72

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  3. Question 3

    A rectangle is 11 cm long and 7 cm wide. What is its area in square centimetres?

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  4. Question 4

    A straight line makes what kind of angle?

    • right angle
    • obtuse angle
    • straight angle

  5. Question 5

    What kind of angle is this?

    • acute
    • right
    • straight
    • obtuse

  6. Question 6

    What kind of angle is this?

    • acute
    • right
    • obtuse
    • straight

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