Topic 10: Length and Area Properties of Two-dimensional Geometrical Figures – Sample Activity

Context

Ampeire is constructing a perimeter wall around her home. She bought 500 bricks for the work but has now realised that the bricks will not be enough for the work. She, therefore, needs to buy more bricks if the construction has to be complete.

Support Material

The wall under construction is 36 metres long and 2.2 metres tall. The bricks being used are each 25 cm long and 12 cm tall.

Task

As the engineer on site, advise Ampeire on an estimate for the number of additional bricks she should buy so as to have the construction completed.

Topic Summary

In this topic, you have learnt that: .

• a two-dimensional (2D) shape has two dimensions that you can measure: you can measure the length and you can measure the breadth (or width) of the shape.
• in general, a 2D shape is a closed flat shape.
• a polygon is a closed flat shape with three or more straight sides. a triangle is a polygon with three sides and three angles.
• a quadrilateral is a polygon with four sides and four angles.
• examples of quadrilaterals include square, rectangle, rhombus, parallelogram and trapezium. a circle is a 2D shape with a curved edge, so a circle is not a polygon.
• area is the amount of flat space taken up by a shape.
• you can use the following formulae to calculate the area of two- dimensional shapes.