New

Year 11

Higher

Checking and securing understanding of changing the subject with simple algebraic fractions

I can change the subject when a simple algebraic fraction is present in an equation or formula.

Download all resources

Share activities with pupils

New

Year 11

Higher

Checking and securing understanding of changing the subject with simple algebraic fractions

I can change the subject when a simple algebraic fraction is present in an equation or formula.

Download all resources

Share activities with pupils

These resources will be removed by end of Summer Term 2025.

Switch to our new teaching resources now - designed by teachers and leading subject experts, and tested in classrooms.

View new resources

Slide deck

Download slide deck

Skip slide deck

Lesson details

Key learning points

It is important to apply the inverse operations in the right order.
The subject can be thought of as the unknown you are trying to find the value of.
Instead of finding a value though, you will find an expression that the unknown is equal to.

Keywords

Subject of an equation/formula - The subject of an equation/a formula is a variable that is expressed in terms of other variables. It should have an exponent of 1 and a coefficient of 1

Common misconception

When rearranging multiplicative relationships, the values just 'swap'.

Pupils should understand how to manipulate multiplicative relationships properly instead of relying on a 'trick'. This will be useful in other subject areas as well.

To help you plan your year 11 maths lesson on: Checking and securing understanding of changing the subject with simple algebraic fractions, download all teaching resources for free and adapt to suit your pupils' needs...

LC2 provides an opportunity to revisit the area of a sector. Pupils could try to write their own formula first. Discuss whether changing the subject or substituting first is the best way to solve questions where they need to find the angle. Substituting first is often easier for foundation pupils.

Teacher tip

Licence

This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

Skip lesson video

Worksheet

Download worksheet

Skip worksheet

Starter quiz

Download starter quiz

6 Questions

Q1.

In which of these formulae is

a

the subject?

a + 1 = b c

Correct answer:

\frac{b + c}{3} = a

a^{2} = c^{2} - b^{2}

b c + 5 = \frac{a}{4}

Correct answer:

a = \frac{2 b + 5}{c (2 - b)} + d

Q2.

Make

x

the subject of

3 x = y + z

x = 3 (y + z)

x = y + z - 2 x

x = \frac{y}{3} + z

Correct answer:

x = \frac{y + z}{3}

Q3.

Make

a

the subject of

4 - a b = c

a = \frac{4}{b c}

Correct answer:

a = \frac{4 - c}{b}

a = \frac{4 + c}{b}

a = \frac{c - 4}{b}

- a = \frac{4 - c}{b}

Q4.

The solution to the equation

\frac{10}{x} = 2

is when

x =

Correct Answer: 5

Q5.

What is the solution to the equation

\frac{5}{x} = 7

Correct answer:

x = \frac{5}{7}

x = \frac{7}{5}

x = 2

x = 35

Q6.

You are given the formula

w = 2 x y + 3 x^{2}

. When

x = 3

and

y = 4

w =

Correct Answer: 51

Exit quiz

Download exit quiz

6 Questions

Q1.

Make

x

the subject of

y = 2 π x

x = \frac{y}{2}

Correct answer:

x = \frac{y}{2 π}

x = \frac{2 y}{π}

x = \frac{π y}{2}

x = y - 2 π

Q2.

Make

h

the subject of

s i n (θ) = \frac{o}{h}

h = o \times s i n (θ)

h = \frac{s i n (θ)}{o}

Correct answer:

h = \frac{o}{s i n (θ)}

\frac{1}{h} = \frac{s i n (θ)}{o}

Q3.

Make

a

the subject of

b = \frac{5}{a + c}

a = \frac{5}{b c}

a = \frac{5}{b} + c

a = \frac{5}{b + c}

a = \frac{5 - c}{b}

Correct answer:

a = \frac{5 - b c}{b}

Q4.

Make

r

the subject of

p = \sqrt{\frac{q}{r}} + 1

Correct answer:

r = \frac{q}{(p - 1)^{2}}

r = \frac{q}{p^{2} - 1}

r = \frac{p^{2}}{q^{2}} - 1

r = \frac{(p - 1)^{2}}{q}

r = \frac{q}{\sqrt{p + 1}}

Q5.

A formula for calculating the perimeter of a rectangle is shown. When

P = 16

and

b = 5

, the value of

a

is .

Correct Answer: 3, a=3

Q6.

The formula for the area of a sector is shown. When the area,

A

, is 110 cm² and the radius,

r

, is 10 cm, the value of

θ

is to the nearest degree.

Correct Answer: 126, 126 degrees

Checking and securing understanding of changing the subject with simple algebraic fractions

Checking and securing understanding of changing the subject with simple algebraic fractions

These resources will be removed by end of Summer Term 2025.

Slide deck

Lesson details

Key learning points

Keywords

Common misconception

How to plan a lesson using our resources

Licence

Lesson video

Worksheet

Starter quiz

6 Questions

Exit quiz

6 Questions