Maths skills in Science - ratios, fractions and percentages
Scientists often have to represent quantities as ratios, fractions or percentages. They
also need to be able to convert between them.
This picture, showing the number of two species in a community can be represented as
a ratio, fraction or a percentage.
Oak Tree
Willow Tree
Ratios show the
relationship between
two amounts
The ratio of oak trees to
willow trees is:
:
Fractions show the
number of parts of a
whole.
The fraction of oak trees
is:
⁄
Percentages show the
number of parts per
hundred.
The percentage of oak
trees is:
%
Task 1
For each example, state whether it is a ratio, fraction, or percentage.
1)
2)
3)
4)
5)
6)
7)
8)
:
⁄
⁄
:
:
%
⁄
. %
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Maths skills in Science - ratios, fractions and percentages
Task 2
Convert these statements from Science lessons into ratios, fractions and percentages
EXAMPLE

Mix one shovel of cement to three shovels of sand
Ratio: :
Fraction: ¼ cement, ¾ sand
NB the 4 on the bottom is because there are a total of 4 parts
Percentages:
% cement,
% sand
NB to calculate these, work out the fraction as a decimal and multiply by 100 (e.g. ¼ = 0.25 x
100 = %)
Context
components
ratio
fraction
_________ daisies
Flowers in a
field
Composition of
air
Nutrients in a
meal
daisies
buttercups
nitrogen
oxygen
other
:
:
________ buttercups
:
percentage
% daisies
% buttercups
⁄
⁄
⁄
⁄
⁄
carbohydrate
protein
fat
other
⁄
⁄
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Maths skills in Science - ratios, fractions and percentages
Task 3 – Challenge
Fractions and ratios should be written in their simplest forms, but always contain whole
numbers only.
If both sides of a ratio (or parts of a fraction) can be divided by the same number to give
whole numbers, you should simplify the ratio or fraction.
For example:
2:4 = 1:2 (divided by 2)
3/6 = 1/2 (divided by 3)
6:9 = 2:3 (divided by 3)
40/100 = 2/5 (divided by 20)
Complete the table to show the missing values – make sure that your ratios and fractions are
in their simplest form.
Values
Ratio
Fraction (give all)
2, 3
:
⁄ , ⁄
4, 8, 12
5, 8, 11
: :
⁄ , ⁄ , ⁄
2, 5, 1
1, 2, 2
Percentages
(give all)
%,
%,
%,
2, 4, 2
30, 15, 45
%,
%,
%,
%,
%
%
%
%
25, 33, 17
66, 33, 11
62, 18, 5
1, 0.5, 0.5
0.5, 1.5, 4.0
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Maths skills in Science - ratios, fractions and percentages
Teaching notes
This task was designed for students to practice using ratios, fractions and percentages.
The resource is ramped in difficulty. It may be that for a quick refresher / assessment for more able
pupils that you want to start straight away with Task 3. Task 1 is a very quick starter activity.
The colour coding aims to help students clearly see the link between the parts of the tasks and go back
to earlier guidance if necessary.
The last two rows of Task 3 involve decimals as a challenge (which is not specifically covered but
should be attempted by the more able).
This resource is one of a set of six resources that are perfectly complemented by our Maths
skills in Science posters. For more information: www.teachitscience.co.uk/maths-skills-inscience-posters
Task 1 – answers
1)
2)
3)
4)
ratio
percentage
fraction
fraction
5)
6)
7)
8)
fraction
ratio
ratio
percentage
Task 2 – answers
Context
components
ratio
Flowers in a
field
daisies
buttercups
:
⁄ daisies
⁄ buttercups
nitrogen
Composition
of air
Nutrients in a
meal
:
oxygen
other
carbohydrate
protein
fat
other
© www.teachitscience.co.uk
:
fraction
:
: :
25139
⁄
⁄
⁄
⁄
⁄
⁄
⁄
percentage
% daisies
% buttercups
%
%
%
%
%
%
%
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Maths skills in Science - ratios, fractions and percentages
Task 3 – answers
Values
Ratio
Fraction (give all)
2, 3
:
⁄ , ⁄
4, 8, 12
5, 8, 11
: :
: :
2, 5, 1
30, 15, 45
66, 33, 11
62, 18, 5
1, 0.5, 0.5
0.5, 1.5, 4.0
© www.teachitscience.co.uk
:
: :
: :
:
: :
: :
⁄
⁄ , ⁄ , ⁄
⁄ , ⁄ , ⁄
: :
2, 4, 2
, ⁄ ,
⁄ , ⁄ , ⁄
: :
1, 2, 2
25, 33, 17
⁄
: :
⁄ , ⁄ , ⁄
⁄ , ⁄ , ⁄
⁄ ,
:
:
⁄
⁄ , ⁄
⁄
,
,
⁄
, ⁄
⁄
25139
%,
%,
%,
%,
%,
⁄
, ⁄ , ⁄
%,
%,
. %,
%
%
%
. %
%,
%
%,
%,
%
%,
%,
%
%,
, ⁄
⁄ , ⁄ , ⁄
Percentages
(give all)
%,
%,
%,
%,
%,
%,
%
%
%, %
%,
%,
%
%
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