Math skills in Science – significant figures
Task 1 – significant figures cards
2479
312
209
72
300
9
3002
0.353
0.4050
0.52
0.70
0.7097
0.703
0.0002
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Math skills in Science – significant figures
Task 2 – significant figures by Donald
Question 1: Here are some measurements taken in a Science lesson. How many significant
figures are in each of these numbers?
Number
Number of
significant figures
1
1
765
3
7000
4
3205
3
5.398
4
0.25
2
0.0003
4
0.500000
1
Marks and comments
___/8
Question 2: Write each of the following numbers to the given number of significant figures.
Number
Number of
significant
figures
Answer
4553
3
455
5390
2
5300
21
1
20
9788
1
9000
0.0000058763
2
0.0000058
0.000030456
2
0.0000304
7.994
2
7.9
3.141592654
4
3.142
Marks and comments
___/8
Feedback for Donald:
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Math skills in Science – significant figures
Teaching notes
This task was designed for students to practice using significant figures. Students ought
to understand the importance of significant figures and you may wish to use this fable as
a starter exercise to explain why it is essential that scientists, engineers, architects etc.
all need to use sensible numbers of significant figures.
www.chemteam.info/SigFigs/SigFigsFable.html
Students should also have already been taught the rules for significant figures. If they
have not, you will need to teach this first. A good summary of the use of significant
figures can be found at
www.bbc.co.uk/schools/gcsebitesize/maths/number/roundestimaterev3.shtml
This resource is one of a set of six resources that perfectly complement our Maths skills
in Science posters, for more information: www.teachitscience.co.uk/maths-skills-inscience-posters
Task 1
Ask students to take a card and state how many significant figures it has and to explain
why. As an alternative give students a set and ask them to sort them into groups of
numbers with 1, 2, 3 or 4 significant figures.
Answers
2479 (4 s.f.)
312 (3 s.f.)
209 (3 s.f.) – as zeros between two significant figures are significant
72 (2 s.f.)
300 (1 s.f.) – as trailing zeros not in the decimal portion are not significant
9 (1 s.f.)
3002 (4 s.f.) – as zeros between two significant figures are significant
0.353 (3 s.f.)
0.4050 (4 s.f.) – as trailing zeros in the decimal portion are significant
0.52 (2 s.f.)
0.70 (2 s.f.) – as 0 is in the decimal portion after a significant figure
0.7097 (4 s.f.)
0.7030 (4 s.f.) – as 0 is in the decimal portion after a significant figure
0.0002 (1 s.f.) – as leading zeros are not significant
Task 2
Ask students to mark Donald’s efforts in the short assessment activity. More able
students will be able to fully assess Donald’s work in the peer assessment activity by
providing constructive feedback on how to improve, rather than simply marking it.
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Math skills in Science – significant figures
Task 2 answers
Number
Number of
significant figures
Expected marking/comments
1
1

765
3

7000
4
x – should be 1 s.f. as trailing zeros are not
significant unless in decimal portion
3205
3
x – should be 4 s.f. as zeros between two
significant figures are significant
5.398
4

0.25
2

0.0003
4
x – should be 1 s.f. as leading zeros are not
significant
0.500000
1
x – should be 6 s.f. as trailing zeros in the decimal
portion are significant
Question 2: Write each of the following numbers to the given number of significant figures.
Number
Number of
significant
figures
Answer
Expected marking / comments
4553
3
455
x – missed off a zero on the end
5390
2
5 300
x – rounded the third digit wrongly
21
1
20

9788
1
9 000
x – this is 1 s.f. but it should be 10 000
0.0000058763
2
0.0000058
x – this is 2 s.f. but it should be 59
0.000030456
2
0.0000304
x - the zero between the 3 and 4 is
significant
7.994
2
7.9
x – incorrect rounding again!
3.141592654
4
3.142
 - Hooray!
General feedback for Donald – his main issue seems to be rounding, but also needs to recheck
the rules – in particular, he’s made two errors with zeros between significant figures.
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