LESSON PLAN

Area Measurement of Squares and Rectangles

Apothem Team

Grade 5 · Measurement

LESSON AT A GLANCE

Warm-up

5 min

Explore

15 min

Consolidate

10 min

Practice

12 min

Exit ticket

3 min

Warm-up

Two rectangles on grid paper: 3 x 8 and 4 x 6. Count tiles for each. (Both have 24 tiles = area 24 sq units.) Calculate perimeters. (3x8: 2x(3+8)=22. 4x6: 2x(4+6)=20.) Same area, different perimeter. Interesting: same area does not mean same perimeter.

Explore

Fixed perimeter investigation: using 24 square tiles arranged as a rectangle, find all rectangles with perimeter 24. (1x11, 2x10, 3x9, 4x8, 5x7, 6x6.) Calculate area for each. Graph: perimeter (constant) on x-axis, area on y-axis. Which rectangle has the greatest area? The square.

Consolidate

Practice

Students calculate area for 6 rectangles/squares, solve 3 missing-dimension problems, and complete the fixed-perimeter investigation. Exit ticket: a rectangle has perimeter 36 cm and length 12 cm. Find the width and area.

Exit ticket

TIP Always include the unit squared label with area answers. An area of 24 cm squared is very different from an area of 24 metres squared. Units matter enormously in measurement.

WORKED EXAMPLES

A square floor has side length 12 m. What is the area?

A = 12 x 12 = 144 m squared. Or: 12 squared = 144.

A rectangle has area 56 cm squared and width 7 cm. What is the length?

A = l x w. 56 = l x 7. l = 56/7 = 8 cm.

MATERIALS

•Square tiles

•Geoboards

•Centimetre grid paper

•Area/perimeter investigation recording sheets

•Traditional dwelling images and context

WATCH FOR

!Students commonly add length and width for area instead of multiplying: 7+8=15 instead of 7x8=56. The formula must be anchored to the counting-tiles model to prevent this.

!Students confuse area units (cm squared) with length units (cm). Area is always measured in square units: it has two dimensions.