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3rd grade · Math · Unit 9 of 14

Area & Perimeter

Around and inside shapes

What your child practices

Finding the perimeter (distance around) of rectangles and triangles, finding a missing side, and measuring area in square centimeters and square meters.

Alabama Course of Study content standard: 3.20; 3.21; 3.22; 3.25 · measuring area with unit squares, relating area to multiplication, and solving perimeter problems

How we explain it

Children can open this short lesson before they practice.

  1. Perimeter is the distance around a shape. Add all sides.
  2. Area is the space inside. Count the square units.
  3. Perimeter uses cm. Area uses square cm.

Example: A rectangle is 5 cm long and 3 cm wide. What is its perimeter? Add all four sides: 5 + 3 + 5 + 3. That is 16 cm. Answer: 16 cm

Area & Perimeter in Alabama

In the Alabama Course of Study, this is unit 9 of 14 in 3rd grade Math, after Round & Count and before Sorting Polygons.

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: Alabama State Department of Education (ALSDE)

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 triangle has sides of 4 cm, 7 cm and 10 cm. What is its perimeter in centimeters?

    answer box

  2. Question 2

    Which rectangle has the same area as a 1 by 20 rectangle?

    • 2 by 11
    • 2 by 10
    • 2 by 20

  3. Question 3

    Each square is 1 square centimeter. What is the area, in square centimeters?

    • 12
    • 11
    • 17

  4. Question 4

    A rectangle is 8 cm long and 7 cm wide. What is its perimeter in centimeters?

    • 30
    • 31
    • 35

  5. Question 5

    Which unit is best for the area of a soccer field?

    • square centimeters
    • meters
    • square meters

  6. Question 6

    A rectangle is 6 cm long and 2 cm wide. What is its area, in square centimeters?

    • 13
    • 12
    • 14

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