Writing essays and
The basics of scientific
writing are always the same, whatever the task. So, we
will focus on essays, including the proper citation of
references - see citing
We start with a short
section on Getting started (overcoming writer's block).
If you don't have this problem then go straight to How to write
Everyone has experienced
writer's block, and that's as true for a first-year essay
as it is for a PhD thesis. It is a psychological hurdle -
the task ahead seems daunting, and you spend ages trying
to decide how you will produce the perfect, polished,
final product. Meanwhile you have produced nothing; you
are no further forward! Or perhaps you do start - you
write the first few paragraphs, you don't feel happy with
them, so you rewrite them again and again, and never make
progress. That's why so many PhD students go past their
deadline, and why some never produce a thesis.
The solution is simple,
and it always works. Let's assume that you have done all
the preparation - you know more or less what you want to
write about, and you have accumulated lots of rough notes
or experimental results, etc.
keep going, and don't look back until you get to the end!
Remember that this is your
first draft, and no-one else will see
it. Don't worry about the finer points of structure.
Don't worry about the order of your sentences - sometimes
the order will be sensible, sometimes not. Don't worry
about your spelling or punctuation. Don't worry if you
can't find the right word or phrase - just use dashes
(--------) or a reminder such as (say something about
dogs here) and keep going. Don't even worry if something
you have written is not strictly true or will need to be
checked. Just keep going!
Once you have produced
this rough draft you will have broken the back of the
job. Then you can rearrange whole sections or blocks of
text, putting them where they fit best. And then you can
go through the text, correcting anything you need to
correct, and inserting anything you need to insert.
Everything that I have
ever written (including two books, more than 100
scientific papers, and even this web site) was produced
initially as a rough draft from start to finish,
and then rewritten or rearranged at least 3
times. The Cut, Copy and Paste
buttons on word-processors make the job easy when you
have got the basic content in place.
How to write a good
important guidance on PLAGIARISM]
requires preparation, organisation and structure.
We don't really need these
things in an email message (although it helps!). We
certainly need them for anything that we want to
"put on record" - an essay, a scientific
|'Far too many relied on
the classic formula of a beginning, a muddle and
draft (see Getting started) might
conform to Philip Larkin's description. Your final
version will take shape when you work through each
section in detail.
makes a good scientific essay?
The answer is: good
structure and good content.
Look at your favourite textbook, or one of the good
review journals such as "Trends" (Trends in
Evolution and Ecology, Trends in Microbiology,
etc.). Why do you like it? Because its structure guides
you through the subject in an accessible way:
sets the scene;
the separate sections
sections are divided into sub-sections, with sub-headings,
so you don't have to plough through long sections
diagrams and photographs
illustrate or summarise key points,
while also breaking the text (textbook editors
are skilled at making the pages appear
puts everything in perspective, and typically
suggests where further work is needed;
cover key areas referred to in the text.
Your essay should have the
same features. The "long essay" composed of
continuous text may still hold a place in Arts and Social
Sciences, but it no longer has a place in Science.
Any piece of writing
should have an Introduction. It need not be long -
perhaps a single paragraph - but it should set the
For a scientific paper
it is usual to give an overview of previous work in
the field, then state why you did your work - e.g. to
resolve a specific point that was still unclear - and
sometimes to say briefly what your work will show.
For an essay
it is usual to define clearly the subject you will
address (e.g. the adaptations of organisms to cold
environments), how you will address this subject
(e.g. by using examples drawn principally from the
Arctic zone) and what you will show or argue (e.g.
that all types of organism, from microbes through to
mammals, have specific adaptations that fit them for
life in cold environments).
The Introduction will
be the first section that you write, but it will
probably be one of the last sections that you revise,
to make sure that it leads the reader clearly into
the details of the subject you have covered.
Introduction start logically by telling us
what the essay is about - for example, the
various adaptations to habitat in the bear
Introduction outline how you will address
this topic - for example, by an overview of
the habitats of bears, followed by in-depth
treatment of some specific adaptations?
(ii) The main body of
The main body of text
should have a clear, obvious structure.
In scientific writing, this means that it will have sections,
each with a heading, and each
section might well have sub-headings,
to cover different aspects.
You will need to think
about the hierarchies of headings,
so that the reader doesn't get lost. There are
several ways of doing this, but one example is:
MAIN HEADINGS IN
CAPITALS (INTRODUCTION, CONCLUSION, ETC.)
Section headings in bold lower case (Mammals
of the temperate zone, Birds,
Sub-sections in italics (The arctic fox,
The polar bear, etc.) or underlined.
You should include tables,
diagrams, and perhaps photographs
in your essay. (See tables, diagrams, photographs). Tables are valuable for summarising
information, and are most likely to impress
if they show the results of relevant experimental
data. Diagrams enable the reader to
visualise things, replacing the need for lengthy
descriptions. Photographs must be selected with care,
to show something meaningful. Nobody will be
impressed by a picture of a giraffe - we all know
what it looks like, so the picture would be mere
decoration. But a detailed picture of a giraffe's
markings might be useful if it illustrates a key
All the points above
refer to structure and presentation. But, of course,
the most important point is that an essay must have substance.
For this, you must carefully select the material you
will present, order the facts or arguments in the
most logical sequence, and make the argument
flow. For example, if you are writing an
essay about adaptations to cold environments, it is
not enough to just piece together a series of
examples - a cold-adapted bacterium, a cold-adapted
moss, a cold-adapted bear, etc. Instead, you should
have chosen your examples to illustrate the
adaptations that they have in common, or the
contrasting ways in which they achieve the same
result, and make these points as you go through the
1. Often you will have
a word limit - say, 2000 words. Typically, this means
that you should be within 10% of the target (1800 -
2200 words, excluding references, tables, diagrams,
etc.). Anything much more, or less, is likely to be
2. How can you cover
anything reasonably in 2000 words, when you could
write at least 10,000 words on the subject? That's
just the point - we (the markers or readers) don't
want to read 10,000 words, and there is no guarantee
that it would be any better than 2000 words. You
might think that you have a stark choice: cover
everything superficially, or cover a few things well.
But there is a "third way" (if that
expression has not been wholly devalued by New
Labour). We can call it "breadth with
depth": cover the main elements of the subject,
then focus on one or two key issues for more detailed
consideration. These issues should be selected
carefully - and say so - for topicality, for the
particular depth of study they have received, etc.
the main body of text
Does your text
have sections with headings and sub-headings?
Does the text
follow a logical sequence, so that the
Does your text
have both breadth and depth - i.e. general
coverage of the major issues, with in-depth
treatment of particularly important points?
Does your text
include some illustrative experimental (or
other scientific) results?
chosen the diagrams or photographs carefully,
to provide information and
understanding, or are the illustrations
(iii) The Conclusion
An essay needs a
conclusion. Like the introduction, this need not be
long, but it should draw the information
together and, ideally, place it in a
conclusion is often the most difficult part of an
essay. Student essays all too often end with some
bland statement such as "As can be seen by the
examples I have discussed, organisms that live in
cold environments usually have specific adaptations
that fit them for these conditions."
That's just words: an
excuse for a conclusion. On the other hand, a
conclusion should not introduce more facts.
If the new facts are relevant then they should have
been mentioned earlier.
The best conclusions
are those that show you are thinking further. For
example, it might be interesting to transfer
cold-adapted organisms to more moderate environments
and see whether the "cold-adapted" traits
are still expressed. Or, it might be interesting to
look for sequence homology in the genes of
cold-adapted organisms and organisms of more moderate
environments. As a last resort, you might use a nice,
short quotation - preferably a witty one to put the
marker in a good mood!
[A note on
conclusions in exam answers. Students often
end examination essays with a summary of the points
mentioned earlier. This is a total waste of time. You
can only score the marks once, no matter how many
times you repeat a point.] Click here for more guidance on
(iv) References and
In all scientific writing you are
expected to cite your main sources of information.
Scientific journals have their own preferred (usually
obligatory) method of doing this. The piece of text
below shows how you can cite work in an essay,
dissertation or thesis. Then you produce an
alphabetical list of references at the end of the
Citations in the text
[We will use colours here, so that you can follow the
guidance notes in the reference list.]
Smith (1999) showed that the ribosomal RNA of
fungi differs from that of slime moulds. This
challenged the previous assumption that slime moulds
are part of the fungal kingdom (Toby
& Dean, 1987). However, according to Bloggs et al. (1999)
the slime moulds can still be accommodated in the
fungal kingdom for convenience. This view has been
challenged by Deacon (1999).
In the reference list at the
end of the essay: [List the references in
Biggles N.H. & Bow R.T. (1999) The
Slime Moulds. Academic Press, London & New
reference is to a book. We give the names of all
authors, the publication date, title, name of
publisher and place of publication. Note that we
referred to Bloggs et al.(1999)
in the text. The term "et al." is
an abbreviation of the Latin et alia
(meaning "and others"). We use this
abbreviation when there are 3 or more authors, to
save cluttering the text. Note also that "Bloggs
et al." is part of a sentence in the
text, so we put only the date in brackets.]
(1999) The Microbial World (http://helios.bto.ed.ac.uk/bto/microbes/microbes.htm)
[accessed 15 November 1999]
reference is to a website. We give the name of the
author (or organisation if there is no author) and
the full URL (web address). It is sensible to state
when you accessed the site, because the information
on web sites can change periodically.]
Jones B.B. and
Smith J.O.E. (1999). Ribosomal RNA of slime
moulds. Journal of Ribosomal RNA 12,
[Guidance: this is a
reference to a published scientific paper. We give
the names of all authors, the date, title of the
paper, the journal, volume number (in bold) and page
numbers (first and last) of the paper.]
Toby F.S. &
Dean P.L. (1987). Slime moulds are part of the
fungal kingdom. In A. E. Edwards & Y.
Kane (eds) The Fungal Kingdom. Osbert
Publishing Co., Luton.
[Guidance: this is a
reference to a chapter in a book edited by Edwards
& Kane. We give the names of all authors, date,
title of the article, editors of the book, title of
the book, publisher and place of publication. Note
how we cited this reference (Toby
& Dean, 1987) in the text. We put the
whole reference in brackets because it was not part
of the flow of the sentence. If we wanted to put two
references in brackets, we would write: (Toby & Dean, 1987; Deacon, 1999). Typically, we
would use chronological order (1987 before 1999) and
separate the two references by a semicolon.
(v) Tables, diagrams, photographs
Tables, diagrams and photographs can be (1) xeroxed
into spaces which you leave in the text, (2) scanned
onto a disk, using a flat-bed scanner, then imported
into a Word document, (3) copied from a WWW source
and imported into a Word document, or (4) xeroxed and
simply glued into your text. [Click here
for guidance on saving and importing images from WWW
sources]. Remember that almost anything you use will
be covered by copyright. It is wise to ask (email)
the owner of a website for permission to use the
image in an essay. In my experience few would refuse
such a "one-off" request.
Labelling, legends and
acknowledgment. Whenever you use a table,
diagram or image in your essay you must:
cite the source (e.g. from
use your own legend
and explanation, not the original
For example: Figure 1. The
pathway of synthesis of the amino acid alanine,
showing...From Bloggs (1989). [Never use the
original legend, because it is likely to have a
different Figure number and to have information that
is not relevant for your purposes. Also, make sure
that you explain any abbreviations or other things
that your reader needs to know about
Often in a scientific essay you will
need to quote sections of other people's work. You do
this in the standard way, by using quotation marks
and citing the source of the information.
For example: Mansell (1999)
stated that "The World is round."
Or: "The World is round."
Be careful not to over-quote. The
best advice is to quote only highly significant
sentences or phrases, not "The world is
round" or "All mammals have fur", nor
points that could be made equally well in your own
words. See the guidance on Plagiarism.
When quoting other people's work, a
few rules must be followed. They are stated
here, then illustrated in an example.
Always quote the words exactly
as the person gave them.
If you need to
miss out parts of the quoted section
because they are not relevant for your
purposes, then use an ellipsis
(three dots). Note that there are no spaces
before or after an ellipsis.
If you need to add your own
words, to make sense of the quoted material,
then put your words in square brackets .
If there is an error in the
quoted material then write '(sic)' after it,
to show that the error is not yours. But this
is most unlikely to arise. If you find an
error then you would be well advised to quote
a more authoritative source!
One of the students wrote
"...the world is like a giant balloon...[that]
spins about it's (sic) axis...[and] orbits the
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