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7th grade · Math · Unit 11 of 22

Nets & Surface Area

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What your child practices

Using nets made of rectangles and triangles to find the surface area of prisms and pyramids.

Texas Essential Knowledge and Skills (TEKS) teks student expectation: 7.9(D) · lateral and total surface area of prisms and pyramids with nets

How we explain it

Children can open this short lesson before they practice.

  1. A net is a solid unfolded flat.
  2. Find the area of every face in the net.
  3. Add them all for the total surface area. Leave out the bases for the lateral surface area.

Example: A box is 2 cm by 3 cm by 4 cm. What is its surface area? Two 2 × 3 faces: 12. Two 2 × 4 faces: 16. Two 3 × 4 faces: 24. 12 + 16 + 24 = 52. Answer: 52 cm²

Nets & Surface Area in Texas

In the Texas Essential Knowledge and Skills (TEKS), this is unit 11 of 22 in 7th grade Math, after Volume and before Probability.

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

    Which shapes make up a net of a triangular prism?

    • 2 triangles and 3 rectangles
    • 1 square and 4 triangles
    • 3 triangles and 2 rectangles
    • 4 triangles

  2. Question 2

    A box is 9 cm by 2 cm by 6 cm. Use its net to find its surface area.

    • 102 cm²
    • 169 cm²
    • 84 cm²
    • 108 cm²
    • 168 cm²

  3. Question 3

    A square pyramid has a base 5 ft on each side. Each triangle face has a height of 9 ft. What is its surface area?

    • 115 ft²
    • 90 ft²
    • 205 ft²
    • 140 ft²
    • 117 ft²

  4. Question 4

    A cube has edges 9 in long. What is its surface area?

    • 486 in²
    • 54 in²
    • 483 in²
    • 729 in²
    • 324 in²

  5. Question 5

    Which shapes make up a net of a triangular prism?

    • 3 triangles and 2 rectangles
    • 1 square and 4 triangles
    • 2 triangles and 3 rectangles
    • 4 triangles

  6. Question 6

    A square pyramid has a base 7 ft on each side. Each triangle face has a height of 7 ft. What is its surface area?

    • 196 ft²
    • 98 ft²
    • 147 ft²
    • 245 ft²
    • 144 ft²

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