Direct proportion in context | Maths | Quizalize & Oak National Academy

Starter quiz

Graphs showing direct proportion have a ______ gradient with an intercept of 0.
- 'positive' ✓
Which of the following graphs does NOT show direct proportion?
Which tables show that A and B are in direct proportion?
The constant of proportionality represented by this graph is ______.
- '2' ✓
Which of the following is NOT true of this graph?
- The constant of proportionality is 0.5
- The gradient of the line is 2 ✓
- The constant of proportionality is 2 ✓
- The graph does show a directly proportional relationship.
- The graph does not show a constant positive gradient. ✓
What are the missing words in this statement? A graph representing direct __________ has a __________ __________ gradient and an __________ of __________.
- relationship, constant positive, intercept, one
- proportion, changing positive, intercept, zero
- proportion, constant positive, intercept, zero ✓
- proportion, constant negative, intercept, zero
- relationship, constant negative, intercept, one

Exit quiz

Two variables are in ______ proportion if they have a constant multiplicative relationship.
- 'direct' ✓
5 miles = 8 kilometres. So 7 miles is ______ kilometres.
- '11.2' ✓
Convert 1 m² into cm².
- 100 cm²
- 1000 cm²
- 10 000 cm² ✓
- 100 000 cm²
- 1 000 000 cm²
The cost of a box of pens is £4.50. Five boxes of pens cost £______.
- '22.50' ✓
If $20 = £15.80, which of the following are true?
- $10 = £7.90 ✓
- $100 = £79 ✓
- $50 = £45.80
- $8 = £3.80
- $200 = £158 ✓
A recipe needs 180 ml of milk to make 15 scones. You can make ______ scones using 6 litres of milk.
- '500' ✓

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Lesson Details

Key learning points

Direct proportion can be used in a number of contexts.
One context is converting compound measure.
Another context is currency conversion.
It is useful to be able to recognise which contexts involve direct proportion.

Common misconception

Assuming that to convert 1 metre squared to cm squared you multiply by 100 and not 10 000

Encourage any pupil who initially finds this challenging to ensure that the values are in the required unit for the answer before doing the calculation.

Keywords

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