Thurs 23rd Feb – Areas and Volumes of similar shapes

LEARNING
OBJECTIVE: TO discover the relationship between the linear enlargement and the area and volume enlargement ratios of similar shapes

SUCCESS
CRITERIA: You will understand what is meant by a similar shape And also understand how to use the linear scale factor of enlargement to work out the area and volume of similar shapes.

STARTER: Write down in a couple of sentences what you understand by the term similar shape. Think of both 2D and 3D shapes

LESSON: Discussion students answers to above starter, discussion on similar shapes.

Copy this table into your text book

Enlargement Scale Factor	Cuboid Dimensions		Total Surface Area	Volume
x 1	2cm x 3cm x 4cm
x 2
x 3
x 5
x 0.5

 
 

1. Work out the total surface area of the cuboid in the first row and put the result in your table
   
2. Do the same for th4e volume of your cuboid and put the result in your table.
   
3. Now double all the lengths of the cuboid and complete the 2^nd row of the table
   
4. Triple the ORIGINAL lengths of the cuboid and then complete the table for the 3^rd row.
   
5. Continue until all rows of your table are completed.
   

Can you spot the relationship between the linear scale factor and the Area scale factor (divide the surface areas by the surface area of the original cuboid in row 1)

Can you spot the relationship between the linear scale factor and the Volume Scale Factor (divide the volume by the volume of the original cuboid in row 1)

Can you summarise and generalise your findings.

Use this lesson (from screen 4) to show how these findings can help solve problems with areas of similar shapes

Use this lesson to show how you can use these findings to solve problems with volumes of similar shapes.

PLENARIES: Answers and Discussions to investigation work, Answer to Mymthas screens on IWB as we work thorugh problems. Summary discussion at end of lesson and get some idea of confidence from students.