← Mathematics — Grade 5/Measurement, Space and Data

Area of Rectangles

≈ 25 min

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Area of Rectangles

Area counts square units covering a surface. For a rectangle, $A=l\times w$ . A careful solution names the quantities, keeps place value or units visible, and explains why each operation fits.

Worked reasoning

Multiply length by width.
$12\times7=84$ square metres.

Key idea

For a rectangle, $A=l\times w$ .

Find the area of a rectangle 12 m by 7 m.

Which statement best captures the central mathematical idea in Area of Rectangles?

For a rectangle, $A=l\times w$ .

A familiar-looking calculation may be used without checking place value, units, conditions or what the answer represents.

A memorised formula is valid even when its conditions are not met.

The diagram or notation replaces the need to justify each mathematical step.

When starting a problem about Area of Rectangles, which move is most reliable?

Represent the given information clearly and identify the operation or relationship required for area of rectangles.

Round every value before identifying the mathematical structure.

Choose the longest available formula and substitute immediately.

Assume the desired conclusion and work backwards without checking equivalence.

Which statement is a misconception that must be rejected when working with Area of Rectangles?

A familiar-looking calculation may be used without checking place value, units, conditions or what the answer represents.

For a rectangle, $A=l\times w$ .

Represent the given information clearly and identify the operation or relationship required for area of rectangles.

Estimate first, then reverse the operation or use a second representation to check that the answer is reasonable.

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