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4th grade · Math · Unit 11 of 15

Angles & Area

Acute, right, obtuse and area

What your child practices

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

Oregon State Standards learning standard: 4.GM.A.1; 4.GM.C.7; 4.GM.B.6 · lines and angles, acute, right and obtuse angles, and the area formula for rectangles

How we explain it

Children can open this short lesson before they practice.

  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 centimeters?

    answer box

  2. Question 2

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

    12 × = 72

    answer box

  3. Question 3

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

    answer box

  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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