Direct and Inverse Proportion with Ratio Tables

• Mathematics
• Upper Secondary (Key Stage 4)
• GCSE

Mastering Direct and Inverse Proportion with Ratio Tables

Direct Proportion

Direct proportion is a relationship between two variables where their ratio is constant.

Time spent reading	10 hours	20 hours	30 hours	50 hours	100 hours	300 hours
books read	2

Inverse Proportion

Inverse proportion is a relationship between two variables where their product is constant.

people building lego	4	2	1	8	5	20
time to complete lego	0.5hrs (30mins)

Ratio Tables

Ratio tables are used to organize and compare the values of two variables in a proportional relationship.

Time spent reading	10 hours	20 hours	30 hours	50 hours	100 hours	300 hours
books read	2	4	6	10	20	60

people building lego	4	2	1	8	5	20
time to complete lego	0.5hrs (30mins)	1hr (60mins)	2hrs (120mins)	0.25hrs (15mins)	24mins	6mins

Solving Direct Proportion Problems

Use ratio tables to solve problems where two quantities are directly proportional.

x	2					4
x 2
y	24					?

Let's have a look at an exam question

What's your answer?

Solving Direct Proportion Problems

Use ratio tables to solve problems where two quantities are directly proportional.

s	20					25
s 2
D	900					?

What's your answer?

Solving Direct Proportion Problems

Use ratio tables to solve problems where two quantities are directly proportional.

h	16					?
g	18					2

√​h​​​

What's your answer?

Solving Inverse Proportion Problems

Apply ratio tables to solve problems involving inverse proportionality between two quantities.

Let's have a look at an exam question

y	9					81
x	12					?

√​y​​​

What's your answer?

Solving Inverse Proportion Problems

Apply ratio tables to solve problems involving inverse proportionality between two quantities.

Let's have a look at an exam question

x	0.2					0.5
x 3
y	250					?

What's your answer?

Write down you main take-away from this lesson.

Have students enter three things they learned in this lesson. With this they can indicate their own learning efficiency of this lesson.

Write down 1 thing you want to know more about.

Here, students enter two things they would like to know more about. This not only increases involvement, but also gives them more ownership.

Ask 1 question about something you haven't quite understood yet.

The students indicate here (in question form) with which part of the material they still have difficulty. For the teacher, this not only provides insight into the extent to which the students understand/master the material, but also a good starting point for the next lesson.