Calculating Perimeter on a Grid

What is the perimeter shape D?

• a) 22 cm

• b) 20 cm

• c) 18 cm

• d) 24 cm

Name the shape and it's perimeter.

• A square and it's perimeter is 15 cm

• A triangle and it's perimeter is 15 cm

• A square and it's perimeter is 16 cm

• A rectangle and it's perimeter is 16 cm

For shape a (green rectangle): ____ cm ____ cm Perimeter = ______cm + ______cm + ______cm + ______cm = ______cm

• 8 cm, 3 cm. Perimeter = 8 cm + 3 cm + 8 cm + 3 cm = 22 cm

• 7 cm, 4 cm. Perimeter = 7 cm + 4 cm + 7 cm + 4 cm = 22 cm

• 8 cm, 2 cm. Perimeter = 8 cm + 2 cm + 8 cm + 2 cm = 20 cm

• 6 cm, 3 cm. Perimeter = 6 cm + 3 cm + 6 cm + 3 cm = 18 cm

For shape c (purple square): ____ cm Perimeter = ______cm + ______cm + ______cm + ______cm = ______cm

• 5 cm. Perimeter = 5 cm + 5 cm + 5 cm + 5 cm = 20 cm

• 4 cm. Perimeter = 4 cm + 4 cm + 4 cm + 4 cm = 16 cm

• 6 cm. Perimeter = 6 cm + 6 cm + 6 cm + 6 cm = 24 cm

• 3 cm. Perimeter = 3 cm + 3 cm + 3 cm + 3 cm = 12 cm

Look at shape a on the grid. The sides are labeled 8cm and 2cm. What is the perimeter of shape a?

• 20cm

• 16cm

• 24cm

• 18cm

Look at shape b on the grid. The sides are labeled 3cm and 6cm. What is the perimeter of shape b?

• 18cm

• 12cm

• 21cm

• 27cm

Look at shape c on the grid. The sides are labeled 3cm. What is the perimeter of shape c?

• 12cm

• 9cm

• 6cm

• 15cm

Look at shape d on the grid. The sides are labeled 6cm and 1cm. What is the perimeter of shape d?

• 14cm

• 12cm

• 16cm

• 18cm

When working out the perimeter of rectangles, which of these statements are true? Tick the statements you agree with.

• length + length + length + length = perimeter

• length + width + length + width = perimeter

• width + length + width + length = perimeter

• length + width + length + length = perimeter

• width + width + length + length = perimeter

Use your statement to calculate the perimeter of this square. (Square: 2cm by 2cm)

• 2cm + 2cm + 2cm + 2cm = 8cm or 4 × 2cm = 8cm

• 2cm + 2cm = 4cm or 2 × 2cm = 4cm

• 2cm × 2cm = 4cm or 4 × 4cm = 16cm

• 2cm + 4cm = 6cm or 2 × 3cm = 6cm