Download Uses of radiation - peer assessment literacy task

Uses of radiation – peer assessment
Task
A GCSE student called Donald was given a test about the uses of
radiation. Below are his answers. Read the questions and his
answers carefully.
Examiner’s notes
Mark Donald’s answers and annotate the paper to show where and
why you have awarded marks. Add notes to show how Donald
could improve his answers.
Uses of radiation test
1. Name the types of ionising radiation. (3)
Alpha and beta.
2. Tick the type of radiation that is correct for each use. (5)
Statement
Sterilisation of medical
equipment
Monitoring the thickness
of paper in a mill
Alpha
Beta


Smoke detector

Imaging diseased body
parts


Treating cancer


Gamma
 
3. Alpha radiation can cause cancer because it is a type of
ionising radiation. However, it is recommended that homes and
offices are fitted with smoke detectors that contain a source of
alpha radiation. Why is this safe? (3)
Alpha radiation is the weakest of the types of radiation so that’s why
it’s used. Smoke detectors are generally on a ceiling and so it just
won’t be possible for the nasty radiation to get out of the smoke
detector and all the way down to you. It’s a small risk to put it there,
but the smoke alarm could help save you from burning in a fire.
4. Describe how the thickness of paper can be controlled using
radiation. (6)
Radiation is fired out of something (the emitter) and then detected by
something (the receiver). The amount of radiation the receiver gets
depends on how thick the paper is. The thicker the paper, the less
radiation gets through.
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Uses of radiation – peer assessment
5. Some people say that heat should be used to sterilise medical
equipment. Suggest an alternative and justify its use. (2)
Examiner’s notes
Use soap. It’s generally cheaper than using all the electricity that
would be needed to heat something to the temperature needed to kill
nasty bugs (bacteria, viruses…). It also smells nice, so it’s like an
added bonus.
6. Describe how ionising radiation is used in a medical setting (3)
Presumably it’s used in their smoke alarms and it will also be used to
sterilise medical equipment such as scalpels and surgical scissors. It
is also sometimes used for treating patients.
7. *Which type of ionising radiation do you think is most
important? Justify your answer with reference to all three types.
(6)
I think that gama radiation is the most important. This is becase it
can be used to treat some cankers. As canker can be a very serious
diseese, gama radiation is very important and has saved many lives
and will continue to do so. The same gama radiation is used to
sterilise medical ekwipment such as scalpuls. Some canker patients
have operations and this means they benefit twice from the gama. If
the scalpuls were not sterilised properly with gama radiation then
they could get an infection, even something like MRSA which could
cause them more problems. Other types of radiation dont have
health benefits and so I dont think they are as important.
Total mark: __/28
Positive comments:
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Targets for improvement:
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Uses of radiation – peer assessment
Teaching notes
This ‘peer-assessment’ task was designed to be used by pupils after they had studied the basics
of ionising radiation (e.g. properties of the three types) as well as their uses. It should be used
to consolidate learning. The resource is designed to address specific misconceptions, errors,
omissions.
Teachit Science resources to support this prior learning include ‘Ionising radiation – jigsaw’,
‘Ionising radiation – questions’ and ‘Ionising radiation – card sort’.
The * in the final question indicates that spelling, punctuation, grammar and use of scientific
terminology will be assessed. Instructions relating to this type of question may be different
depending on exam board, these could be added to the resource before printing.
If you wish to give pupils a resource to read prior to the task or to refer to during the task, the
following website link has appropriate material
http://www.bbc.co.uk/education/guides/zkktyrd/revision/1 (link available at time of
publishing).
Pupils of GCSE age are notoriously critical. They take delight in noticing Donald’s errors,
misconceptions and lack of exam technique. Sometimes however, Donald surprises the students
with a great answer!
Donald’s work was designed to review ionising radiation in the Edexcel Additional Science
specification Topic P2. However, specification content for these concepts varies little between
exam boards.
To stimulate discussion, Donald’s work can be used in pair or small group work, followed by
targeted whole class questioning.
The following marks and comments are expected from pupils:
1. Donald would score 2 marks on this question.
Donald should have taken note of the ‘3’ marks and this should have prompted him to realise
that he probably needs more than two answers!
2. Donald would likely score 2 marks in this question.
On the first line, Donald hasn’t selected an answer – this is very silly – an opportunity to remind
pupils that there is nothing to be lost by answering the question. The answer is gamma for
sterilisation.
On the second line, he scores no marks because he’s crossed out both his answers – it should be
beta used for monitoring paper thickness.
The third line is correct – alpha is used for smoke detectors.
On the fourth line, Donald has chosen two answers, which does not match the instructions
which say the type not types. He scores zero for this line.
On the fifth line, despite all the crossing out, Donald is correct that gamma is used to treat
cancer.
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Uses of radiation – peer assessment
3. Donald would be lucky to score just 1 mark.
Donald is wrong about alpha being the weakest type of radiation. He might have meant to write
that it can travel the least far of the types of ionising radiation – this would score a mark. He
could also have scored a mark for explaining why it doesn’t travel very far – because it is
strongly absorbed by air or because it can’t penetrate air very well. The third mark would then
be for linking this to safety e.g. recognising the distance between the user and the smoke
detector or recognising the huge benefit over the tiny risk.
4. Although Donald’s answer is brief, he may score 4 marks.
He would be credited for the idea of sending out (emitting) and detecting the radiation. Also,
Donald has done well to give a pattern – “thicker the paper, the less radiation gets through”.
However, Donald loses marks because he has not stated the type of radiation that is used (beta)
or linked the idea that the amount of radiation getting through will then be used to alter the
paper thickness. His use of scientific terminology here is good and so 4 rather than 3 marks is
justified. A diagram could have helped to illustrate his answer.
5. Donald has not thought about what he has learnt in Science! The answer isn’t completely
daft, but it’s not very scientific. He would score 0 marks.
Donald should have remembered that gamma radiation is used to sterilised medical equipment.
It is used because it won’t melt plastic equipment unlike heat. Credit could also be given for
saying that it uses less energy.
6. Whilst Donald’s answer is true, the question is after medical uses, rather than side issues
such as hospitals needing smoke alarms. He might score 1 mark for the sterilisation
statement but he hasn’t said which type is used (gamma).
Donald should also know that gamma radiation is used to treat some cancer patients and that
beta is used as a medical tracer to image damaged or diseased body parts.
7. The content of Donald’s answer is reasonable, but he has neglected to reference the other
types of radiation, as actually requested in the question. He may however score 3 marks as
he has described two important uses of his chosen type of radiation. His poor SPaG has cost
him the fourth mark!
To gain the full credit he should justify why alpha/beta are less important.
Overall, Donald would score (at most) thirteen marks.
Positive comments:
Donald’s spelling is generally very good, but perhaps he didn’t use a dictionary to check his
spelling in the last question.
Targets for improvement:
He needs to focus on ensuring that his answers match the question given. This includes
completing all questions and re-reading questions to check that he has done everything asked of
him. Donald also needs to make sure that he is always considering whether his answers are about
what he has learnt in Science lessons (e.g. the sterilisation/soap answer).
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