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4th grade · Math · Unit 11 of 17

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.

Texas Essential Knowledge and Skills (TEKS) teks student expectation: 4.6(A); 4.5(D) · points, lines, rays and angles, and the area of 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

Angles & Area in Texas

In the Texas Essential Knowledge and Skills (TEKS), this is unit 11 of 17 in 4th grade Math, after Equations and before Polygons & Perimeter.

Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.

Source: Texas Education Agency (TEA)

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

    What kind of angle is this?

    • right
    • acute
    • straight
    • obtuse

  2. Question 2

    A rectangle is 13 cm long and 4 cm wide. What is its area in square centimeters?

    answer box

  3. Question 3

    What kind of angle is this?

    • obtuse
    • right
    • straight
    • acute

  4. Question 4

    A straight line makes what kind of angle?

    • obtuse angle
    • straight angle
    • right angle

  5. Question 5

    A rectangle has an area of 70 square centimeters. It is 10 cm long. How wide is it, in centimeters?

    10 × = 70

    answer box

  6. Question 6

    A rectangle is 14 cm long and 4 cm wide. What is its area in square centimeters?

    answer box

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