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# 2.30 Multiplicative contexts: area and perimeter 2

Created on 28 August 2019 by ncetm_administrator
Updated on 03 September 2019 by ncetm_administrator

## Introduction

Build on earlier knowledge of area and perimeter. Learn to find the area of parallelograms and triangles by identifying the perpendicular height. Compare areas and perimeters and apply scale factors to side-length, perimeter and area.

## Teaching points

• Teaching point 1: The area of a parallelogram can be calculated by multiplying the base by the perpendicular height; all parallelograms with the same base and perpendicular height will have the same area.

• Teaching point 2: The area of a triangle can be calculated by multiplying the base by the perpendicular height and then dividing by two.

• Teaching point 3: Shapes with the same area can have different perimeters; shapes with the same perimeter can have different areas.

• Teaching point 4: When a shape has been transformed by a scale factor, the perimeter is also transformed by the same scale factor.

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