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Lesson · Grade 6 · Mathematics

Area of a Parallelogram: Cut and Slide into a Rectangle

  • Grade 6
  • Mathematics
  • 1 min 14 s
  • British Columbia
  • BC6-MA-30

A parallelogram with a 7 cm base and a 4 cm height has a triangle cut off along its height, and the triangle slides to the other end to make a rectangle with the same area. The rectangle's area is 7 × 4 = 28 cm², which a grid of 1 cm squares confirms, so the area of any parallelogram is base × height.

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In one sentence

The question this lesson answers

What is the area of this parallelogram?

Its base is 7 centimetres long.

Transcript

What the lesson says

What is the area of this parallelogram?

Its base is 7 centimetres long.

Its height is 4 centimetres, measured at a right angle to the base.

The slanted side is longer than the height.

Cut off the triangle along the height line.

Slide the triangle to the other end.

It fits exactly and makes a rectangle.

Nothing was added or taken away, so the area is the same.

The rectangle has the same base, 7 centimetres, and the same height, 4 centimetres.

Its area is 7 times 4, which is 28 square centimetres.

Check: 4 rows of 7 square centimetres make 28 square centimetres.

So the parallelogram's area is also 28 square centimetres.

For any parallelogram, the area is base times height.

Remember: cut and slide a parallelogram into a rectangle, and its area is base times height.

Curriculum

Where this fits

British Columbia, Grade 6

Mathematics, Geometry and measurement: area of triangles, parallelograms, and trapezoidsBC6-MA-30

Previous: Perimeter of a Complex Shape: Find the Missing Sides FirstNext: Area of a Triangle: Half of a Parallelogram

The outcomes and strands follow the British Columbia curriculum.

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