Some reflections on Unit 6 – June 2011 (Ed Lees – Principal Examiner/Moderator Unit 6)
Introduction
The Edexcel GCE from 2008 specification (8BI01/9BI01) is a development from the previous Edexcel
and SNAB specifications. It is a single OfQUAL approved award and as such has ‘How Science Works’
as an important underlying principle. Unit 6 is the main vehicle for assessment of HSW and hence,
whilst many of the criteria are very similar to the outgoing SNAB specification particular emphasis
has to be placed on the evidence for HSW. The comments on each criterion which follow indicate
some of the areas where this is particularly important.
These changes were explained in the original Unit 6 Teachers Guide which has now been
superseded by the documents described below. New exemplar material (Dec 2010) and the
examiners/moderators reports for June 2010 and June 2011 were all carefully compiled in the light
of the first cohorts to sit this paper. All are available for download from the Edexcel website. They
are the only definitive documents explaining how the criteria are applied by examiners/moderators.
There was some evidence that this advice had been acted upon by many centres but a significant
minority did not appear to be aware of some of the standards applied.
Above all Unit 6 is a real opportunity for candidates to investigate some interesting aspect of biology
and demonstrate the skills they have acquired throughout the course rather than search for
something to copy and attempt a simple demonstration of what they perceive as a well-known
‘fact’.
Quality Judgements
During internal assessment it is always useful to bear in mind the following grade boundaries.
Unit 6 Grade boundaries – June 2011
Grade
Max
A*
A
B
C
D
E
Raw mark
45
38
33
28
24
20
16
It is logical therefore to assume that any investigation awarded above a total of 33 is regarded as of
very high A2 level standard and that any reports achieving 38 or more are of the highest quality we
might expect of an A2 candidate. Centres where this relationship was well-understood were often in
close agreement with moderators, which was not the case where marks had been awarded without
applying such judgements.
Individual work
It is a fundamental feature of all examinations that they provide clear evidence of the candidates’
individual skills on which the examiner can award credit. The trial investigation for P(c) is a key area
of evidence here. This can cause significant problems to examiners/moderators. Whilst not wishing
to penalise candidates, examiners cannot award credit where it is not possible to distinguish
individual contributions. There are two main areas where this can be of concern.
(a) Repeating core practicals
Examiners/moderators reports and guidance documents have repeatedly stressed that since
all candidates have a signed document to verify that they have completed the core practical
requirements we will assume that they have detailed guidance on all of these procedures. If
these are simply repeated for Unit 6 then they must show that they have planned further
extensions of these in such a way that their own skills are evident. Much of the evidence for
this will come from the development of trials.
Some reflections on Unit 6 – June 2011
Ed Lees – Principal Examiner/Moderator Unit 6 – 17.10.11
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Many candidates submitted investigations using bacterial lawns which demonstrated a poor
understanding of the principles of this technique (diffusion through an aqueous medium)
and no testing of the most reliable way of collecting data. They merely added an assortment
of mouthwashes or hand washes with little regard for their contents or how they could be
compared reliably.
(b) Identical approaches to similar investigations
This was sometimes a problem with fieldwork where large groups followed identical
standard procedures and, in extreme cases, identical trials. Many centres used the excellent
opportunities offered by outdoor habitats to allow candidates to think for themselves and
investigate interesting ideas. A limiting factor for others seemed to be a lack of time
allocated to planning and trialling ideas. There was some evidence that where, for
understandable reasons, field courses are timed at the end of the AS course or very early in
the A2 year candidates found difficulty in demonstrating the progression required for high
A2 grades. Where this timing is inevitable, then it is vital that the development of the
required skills is given careful attention throughout the AS course.
Research & rationale
It is important that students are aware that their research needs to address two points. What is the
biological basis of my investigation? Why might what I am investigating be regarded as interesting by
other biologists? How this is applied will depend on the investigation but the latter need not be
extensive, merely place the purpose of the investigation in a wider context. The biology behind the
hypothesis needs to be more accurate and relevant as it will be required to inform the plan and
interpretation of results.
Planning
This is the most important section of the investigation. P(a) and P(c) provide key evidence of HSW
criteria and are obviously interlinked. It is in this section that the evidence in the report will
differentiate candidates who are thinking independently and objectively from those who are simply
attempting to follow a ready-made solution. The focus of a trial should be on the main dependent
and independent variables. Precisely how are these to be measured accurately and reliably? Am I
actually measuring what I think I am measuring? This does not necessarily need a great deal of time
but we do need to see the evidence on which any decisions are based. Two simple examples might
illustrate this.
 Many candidates investigate the effects of light in ecological situations but only a tiny number
give any thought to the problems involved. There are many ways of testing or devising a method
that will at least be more reliable than simply holding out a light meter. E.g reflected or direct
light? Use a running mean to decide how many readings to take. Thinking about effect of time of
day and aspect. Etc.
 Clearance of bacterial lawns is variable. Does measuring area or diameter make a difference?
Does the size stabilise? After how long? Should the disc/well be included in the measurements?
Does it make a difference?
Observing
It is a requirement for O(b)3-6 that ‘Any anomalous results are noted’. For the highest mark ranges it
would be expected that some action is taken where anomalies are recorded. This is an area where
progression to high A2 levels might be apparent, with more able candidates showing an
understanding of the meaning of standard deviations or using analysis to define an anomaly. If there
are no anomalies then a brief explanation of how this decision was reached would be needed.
Some reflections on Unit 6 – June 2011
Ed Lees – Principal Examiner/Moderator Unit 6 – 17.10.11
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Interpreting & Evaluation
I(a) continues to be clearly applied by most, although some evidence of calculation is required. I(b)
improved considerably in June 2011 but only more able candidates used their research to show a
clear understanding of the actual data collected.
There were very many disappointing attempts at evaluating for I(c). Weak GCSE standard comments
concerning collecting more data or pointing out serious errors in their own plan were common. Only
a very small minority of higher-scoring candidates attempted an analytical approach using evidence
from their data and objective scientific thinking. This section should provide important evidence of
the application of HSW skills which are clearly listed in both the specification and the December
2010 exemplar material.
Communicating
C(b) Bibliographies were often extremely vague and did not give sufficient information to make a
judgement as to their scientific credibility. Most consisted largely of web addresses from a search
engine with no information to identify the articles, their author or source. It was not uncommon for
a journal reference to have neither the journal nor the paper title. Several journal references also
appeared to extremely tenuous links to the hypothesis under test. This weakness was linked to the
difficulty many found in evaluating sources. A good example of this naivety was shown where
attempts to cross-reference researched information merely named several search sites which
inevitably gave the same single source.
Some reflections on Unit 6 – June 2011
Ed Lees – Principal Examiner/Moderator Unit 6 – 17.10.11
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