New
New
Year 10
Higher

Checking and securing understanding of direct proportion in context

I can recognise direct proportion in a range of contexts, including compound measures.

New
New
Year 10
Higher

Checking and securing understanding of direct proportion in context

I can recognise direct proportion in a range of contexts, including compound measures.

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Lesson details

Key learning points

  1. Direct proportion can be used in a number of contexts.
  2. One context is converting compound measure.
  3. Another is currency conversion.
  4. Regardless of the context, if one quantity is zero, the other must be as well.
  5. It is useful to be able to recognise which contexts involve direct proportion.

Keywords

  • Direct proportion - Two variables are in direct proportion if they have a constant multiplicative relationship.

Common misconception

All straight line graphs show direct proportion.

Only straight line graphs that pass through the origin (0, 0) show direct proportion.

A non-linear relationship between two variables means they are not directly proportional to each other. For example, there is a non-linear relationship between the radius and area of a sector. However, there does exist direct proportionality between the radius² and the area of that sector.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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6 Questions

Q1.
Two variables are in proportion if they have a constant multiplicative relationship.
Correct Answer: direct
Q2.
Four friends went to the cinema. The cost of their tickets was £38. How much did each ticket cost? £
Correct Answer: 9.50, £9.50
Q3.
In a supermarket, 3 tins of soup cost £4.80. 8 tins of the same soup should cost £
Correct Answer: 12.80, £12.80
Q4.
Match each measurement to its equivalent measurement.
Correct Answer:3.3 cm,33 mm

33 mm

Correct Answer:303 cm,3.03 m

3.03 m

Correct Answer:3.3 mm,0.33 cm

0.33 cm

Correct Answer:3.3 m,3300 mm

3300 mm

Correct Answer:0.033 km,3300 cm

3300 cm

Q5.
Calculate the volume of this cuboid.
An image in a quiz
Correct answer: 0.09 m³
0.9 m³
9 m³
1.47 m³
132.15 m³
Q6.
Calculate the surface area of this cuboid.
An image in a quiz
0.09 m²
0.735 m²
Correct answer: 1.47 m²
2.94 m²

6 Questions

Q1.
Two variables are in direct proportion if they have a __________ relationship.
additive
Correct answer: constant additive
constant multiplicative
multiplicative
Q2.
Which of these graphs shows direct proportion between the two variables?
An image in a quiz
An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
Q3.
The ratio table shows the conversion €7 (Euros) = £6 (Pounds Sterling). €630 = £
An image in a quiz
Correct Answer: 540
Q4.
The perimeter of a triangle is 33 300 cm. Which calculation shows its perimeter in metres?
33 300 cm ÷ 10
Correct answer: 33 300 cm ÷ 100
33 300 cm ÷ (3 × 100)
33 300 cm ÷ 100 ÷ 100 ÷ 100
Q5.
A circular sector with an angle of 60° has a radius of 6 cm, an arc length of 2π cm and an area of 6π cm². Select the correct statements.
An image in a quiz
Correct answer: The arc length is directly proportional to the radius.
The area is directly proportional to the radius.
Correct answer: If the radius is doubled, the arc length will be 4π cm
If the radius is doubled, the area will be 12π cm².
Q6.
The area of a triangle is 600 cm². The area of the triangle in metres squared is m².
Correct Answer: 0.06, .06