# The constant of proportionality

## Lesson details

### Key learning points

1. In this lesson, we will learn about the the term 'constant of proportionality' and how it relates to how proportion works.

### Licence

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## Video

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## Worksheet

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## Starter quiz

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### 5 Questions

Q1.
Which graph does not show to direct proportion?
A
B
Q2.
Which graph shows direct proportion?
B
C
Q3.
Which table does not shows direct proportion?
A
B
Q4.
Which table does not shows direct proportion?
B
C
Q5.
x and y are directly proportional as shown in the graph. What is the value of y when x = 10?
20
22

## Exit quiz

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### 8 Questions

Q1.
Complete the sentence: When two quantities are in ........................ , when one variable doubles, the other doubles too.
constant of proportionality
indirect proportion
Q2.
Complete the sentence: When two quantities are in direction proportion, when one variable is zero, the other is .............
10
2
Q3.
x and y are in direction proportion. When x is 4 y is 11. What is the value of y when x = 12?
23
5
Q4.
The cost of T shirts online at £12 each. The postage charge is £3.50 per order. How much will it cost to order 2 T shirts?
£24
£31
Q5.
Think about the previous question: Are the number of T-shirts and the cost in direct proportion?
Yes
Q6.
Which table shows direct proportion?
Option 2
Option 3
Q7.
What is the constant of proportionality in the table below?
10
2