1. Identify and construct enlargements using fractional scale factors.
Grade 5
Enlargement
Identify and construct enlargements using fractional scale factors.
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2. Lesson Plan Lesson Overview Progression of Learning
Objective(s)
Identify and construct enlargements using fractional scale factors
Grade 5
Prior Knowledge
Simple enlargements
Scale factors
Finding fractions of amounts
Duration
Lesson objective can be covered within 50 minutes provided students are confident with positive scale factor enlargements.
Resources
Print slides: 5, 12, 18, 19
Equipment
Ruler
Progression of Learning
What are the students learning?
How are the students learning? (Activities & Differentiation)
Starter – finding fractions of amounts
Quick recap – how to find a fraction of an amount – will be needed when applying the scale factor to the lengths of shapes.
How to do and describe a enlargement
(positive integer scale factor)
Give students slide 5 printed. Variations here with or without a centre of enlargement. Discuss scale factor and positioning of the enlarged shape. Describing often helpful to have a ruler. 15
Scale factor
Give students slide 12 printed. Show students how scale factors are calculated. Discuss that enlargement does not necessarily mean that the shape gets larger. Practice finding the scale factors.
Constructing enlargements with fractional scale factors
Give students slide 18 printed. Students to complete independently using notes created from above. Draw on solutions using interactive whiteboard. 10
Constructing enlargements with fractional scale factors in OCR exam questions (from specimen papers)
Give students slide 19. This includes an exam questions related to objective. Students need to use notes from lesson to answer the questions. Ensure that all steps are shown. Relate to mark scheme to show how the marks are allocated.
Next Steps
Negative and fractional scale factors for enlargement
Assessment
PLC/Reformed Specification/Target 5/Geometry and Measures/Enlargements Fractional SF

3. Starter
– finding fractions of amounts
1 4 of 4
1 4 of 8
1 2 of 4
1 3 of 9
1 2 of 6
1 3 of 3 2 3 1 3 1 2

4. Key Vocabulary
Centre Enlargement Scale factor Multiple Similar

5. Describe Transformation
Enlargement
Enlarge scale factor 2, centre A (1,1)
Enlarge
scale factor 2
Enlarge scale factor 3, centre (1,2)
Describe Transformation 1. 2. 3. 1. 2. 3.
Student Sheet 1

6. Enlargement Solutions
Enlarge scale factor 2

7. Enlarge scale factor 3, centre (1,2)
Enlargement Solutions
Enlarge scale factor 3, centre (1,2)
Visualier
Guide

8. Enlarge scale factor 2, centre A (1,1)
Enlargement Solutions
Enlarge scale factor 2, centre A (1,1)
1 min head start

9. Describe Transformation
Enlargement Solutions
Describe Transformation 4
1. Enlargement
2. Scale Factor 4
3. Centre (1,1)
Guide vis 8 1 2

10. Describe Transformation
Enlargement Solutions
Describe Transformation 5
1. Enlargement
2. Scale factor 2.5
3. Centre (0, 0)
1 min head start 2

11. Find by measuring the length or counting the squares
Fractional Scale Factor
A scale factor is the number of times bigger an image is than the object. 5
Find by measuring the length or counting the squares 2
5cm÷2cm
Or 5 2
Or 2.5
1 min head start

12. Fractional Scale Factor
Calculate the scale factor of the following with the object being the first information and the image the second:
A to B B to A A to C C to A
B to C C to B A to D D to A
B to D C to D A B
The scale factor is 2/3, draw the image: D C
Student Sheet 2

13. Fractional Scale Factor
On a grid, you count squares:
The scale factor here
Is or 1.5.
2 squares
3 squares

14. Fractional Scale Factor
If you have the object and the scale factor you can draw the image:
The scale factor is 2/3, draw the image:
The base is 6 squares, 2/3 of this is 4.
The height is 3 squares, 2/3 of this is 2.

15. Practice – Scale Factors
Calculate the scale factor of the following with the object being the first information and the image the second:
A to B
B to A
A to C
C to A
B to C
C to B
A to D
D to A
B to D
C to D A B D C

16. Practice – Scale Factors
Calculate the scale factor of the following with the object being the first information and the image the second:
A to B
B to A
A to C
C to A
B to C
C to B
A to D
D to A
B to D
C to D
3/2
2/3
3/5
5/3
2/5
5/2 2
1/2
4/3
10/3 A B C D

17. Reasoning. In the practice exercise, mapping A on to B gave the reciprocal of mapping B to A. Why is this? Because you have to do image/object to get the scale factor, when they are swapped, the fractions will also swap – so the reciprocal is taken.

18. Practice – Doing Enlargements
Student Sheet 3

19. Exam Questions – Specimen Papers
Student Sheet 4

20. Exam Questions – Specimen Papers