Hi, I’m Frankie Annets. I am the Assistant Principle Examiner for GCSE Sciences. I’m
here today to talk to you about the maths assessment skills in the papers that you are
going to sit. In Biology 10 % of the marks will be maths,
in chemistry 20% and physics it will be 30%. Sometimes it looks like there are more maths
than this on a paper. That’s because Ofqual don’t always accept that some of the maths
counts as maths. Its got to be at least KS3 standard for foundation tier paper and keystage
4 foundation maths for higher papers. So sometimes what looks like maths will actually be testing
the Science. In the paper you might get something, for example a resistance of a wire equation
and a couple of bulbs in that circuit and so you have to divide by 2 because there’s
two bulbs, that’s Science and not maths. So, what we are going to look at today are
some maths skills and I’ve got some exemplar papers for you.
The maths skill in the first question is using percentages. The command word is calculate
and you have to apply knowledge and understanding to do this, so this targets AO2.
There are 2 marks for this question. This means you need to carry out 2 steps to get
all the marks. It is important to read the question carefully
so you can decide which numbers you need to use in the calculation. The question tells
us the number of cases of scarlet fever in March 2013 and March 2015. It is asking for
the percentage increase between these two figures.
So when you are doing any calculation question its important to show your working, even if
the question doesn’t ask you to. This is because you might be able to carry out a calculation
in your head or you might use a calculator but you also could make a mistake, that could
be a mistake in the calculation or sometimes its just a mistake copying a number down from
a calculator onto the paper. If you’ve shown every step the examiner can see where you’ve
gone wrong, but they can also see the things that you’ve done right and they may be able
to award the marks to you for those right things.
You may want to pause the video for a few minutes to attempt this question
Here is the mark scheme for 3aii. The first step is a subtraction.
The second step is the percentage increase calculation.
So if you made a mistake in the first step but used the answer from your first step correctly,
in the second step you could still gain a mark. This is called an error carried forward.
Here is an example of a 1 mark answer. The candidate calculated or possibly just
wrote down from the calculator the incorrect number for the first step. They used this
number correctly in the second step and so still got 1 mark even though the overall answer
is wrong Here is a fully correct answer
The candidate showed their working to get the correct answer for both marks. They also
wrote %. They did not need to do this as the units were given. If ever you need to write
the units the question will ask you to ‘show the units’ and you will get a mark for it.
The second question is about speed of light. The equation is actually given so what the
candidates have to do is choose the correct numbers from the question and put them into
the equation. This means that they are applying their knowledge and using their skills which
means it’s an AO2 question. The numbers are given in standard form and
many candidates struggled with this last year. It is a good idea to practice using standard
form on calculators so that this type of question would not cause you an issue.
There are 3 marks available here. The first two marks are for the calculation. However,
if you have read the question carefully you would have spotted that you have been asked
to ‘State the unit.’ This means the third mark is for giving the correct unit. This
is not a maths mark. This tests your knowledge of the unit of frequency.
You have to substitute the correct numbers into the frequency equation and then calculate
the answer from that. You must also give the unit. Again it is important to show your working,
You may want to pause the video for a few minutes to attempt this question
So here’s the mark scheme for question 5b. The first mark is for substituting the numbers
into the frequency equation. The second is for the correct answer. The third mark is
for the correct unit. Here is an example of a 3-mark answer. So, the 3.0 x108 over 5.8
x 107 is a marking point 1. That’s where they substituted the correct numbers into
the equation. The answer of 5.2 x 10 14 is mark point 2 so that’s the evaluation of
this answer. And then Hz or hertz is mark point 2. They could have spelt it out, but
you don’t need to. This question tests the understanding of magnification
and standard form. In this case an equation is not given.
The calculation in this question is quite simple and understanding how to calculate
magnification is a science point. However, the second part of the question asks for the
answer in standard form. This is a maths mark. There are 2 marks here. One mark is for calculating
the width of the cell. The other mark is for giving the width in standard form. Again it
is really important to show your working You may want to pause the video for a few
minutes to attempt this question Here is the mark scheme for 5aiii. Here is
an example of a 2 mark answer. If you have a look the candidate did show their working.
First they calculated the width, and then in the second step they converted their answer
to standard form. So they have gone from 0.0077 to 7.7 x 10-3 .Its a really good idea to practice
converting numbers to standard form. The next question is 3e from the chemistry
foundation paper. In this question you’ll need an understanding
of significant figures, this is AO2. This question asks for the answer to two significant
figures. There are 3 marks here, 2 marks for calculating the barrels and one mark for converting
the answer to significant figures, so it’s a really good idea to practice doing this.
So you may want to pause the video for a few minutes to attempt this question. Remember
its really important to show your working. Here is the mark scheme for 3e.
Here is an example of a 3 mark answer.
The candidate showed their working. First they calculated how many barrels equalled
1%. for a mark. Then they calculated the number of barrels of fuel for the second mark.
They converted their answer into 2 sig figs for a final mark.
This shows it is important to show working as if they had made a calculation error it
would still be possible to gain the final mark if the answer was to 2 sig figs
A question might also ask you to give an answer to a specific number of decimal places like
to 2 decimal places for example. If you do see that just treat in in exactly the same
way as if they’d asked you for a specific amount of significant figures. Occasionally
you get a question with a table of results in with one of the results missing, just make
sure that the number you fill in is to the same number of decimal places.
So an example of this is from question 5b ii from biology higher paper 1. The table
gives rate to 3 decimal places and so you should give the rate you have calculated to
the same number of decimal places.
The sixth question is 5d from the chemistry foundation paper 1.
This question tests the understanding of calculations needed when making up solutions. An equation
is not given and in fact there are several ways to answer this question.
Where the equation is not given it is often a good idea to write out the equation you
will use if there is one. Then substitute the numbers into the equation. It is also
important to check the units. The volume was given in the question in cm3 but the units
for the answer is g dm-3. This means you will need to convert cm3 to dm3.
You can use the units to help work out what equation to use. g dm-3 means that something
measured in g must be divided by something measured in dm3.
There are 2 marks here, one mark is for converting cm3 to dm3. This involves dividing or multiplying
by 1000 depending on the method you use. The other mark is for calculating the concentration.
Again it is really important to show your working
You might want to stop the video now to have a go at this question. If you are not sure
about what equation to use, you can sometimes use the units. So in this case the grams per
decimetre cubed means that something in grams has to be divided by something in decimetres
cubed. Here is the mark scheme for 5d and here is
an example of a 2 mark answer. The candidate showed their working. There
was no mark for the equation but it helped the candidate . First they calculated the
concentration in g cm-3 and then in the second step they converted their answer to g dm-3
by multiplying by 1000. So hopefully that’s answered some of your
questions about how to answer these maths skills questions. Just before the canteen
completely closes up I’ll just go through some of those key points for you. So first
of all look at the question, what is it asking you to do, what is it asking you to calculate?
What are the numbers that you are meant to use? Often there are lots of numbers in the
question, try and pick out the ones which are actually key to answering the question.
Do you need to know an equation and do you need to use an equation. What do you need
to do with that? Also what are the units and does your answer match the units, make sure
that it makes sense. The question might ask for it in standard form or significant figures
or decimal places, read that on the question carefully and make sure you do what it asks
you to do. And most importantly show your working if you show your working and you get
some of the answer right you will get some marks. So that was quite a lot of information
for you. Don’t worry if you don’t remember it all we have the Edexcel website that has
a lot of information, so go to the GCSE Science website where you can find past papers where
you can practice these skills and guidance on how to do your exams. So good luck.
Summary The following are key to think about when
answering a maths skills question - what am I being asked to calculate?
- what numbers from the question do I need to use?
- what are the units/does my answer match the unit given?
- how many marks are there/how many steps are there?
- do I need to give my answer in standard form, specific number of significant figures/
specific number of decimal places? - have I shown my working?