Formal Laboratory Report Style Guide
Formal Laboratory Report Style Guide
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When you do experiments, you write them up in your lab notebook, which
is a kind of personal journal of the experiments you have done. A
formal lab report is how you communicate the details of your experiment
to the outside world.
There are many ways of writing up a laboratory experiment. You have
probably already done several different forms, in your ninth grade
science and biology classes. The format we will use in this class is
called "journal article format," because it is the same format that
scientific journals require for published articles. More practically,
it is the format required by most colleges. It more or less resembles
the format of an English term paper.
A standard journal article laboratory report is organized into the
- A single sentence fragment (no verb) that describes your
experimental objective and gives some indication of the method
- A one-paragraph summary of the entire
experiment-your procedure, results, and analysis.
- A description of the scientific background for
for your experiment, including any previous experiments that your
experiment builds on. (Remember to cite your sources!) The final
sentence (analogous to the thesis statement in a term paper) is the
objective of your experiment.
- Materials and Methods:
- A detailed description (in paragraph
format) of the procedure for your experiment.
- Your data, as you observed/recorded them. Note that
this section is only for data that you observed or measured
directly. Your analysis (including calculations) belongs in the
- Your calculations, an analysis of what your
results mean, and your error analysis.
- A short paragraph that restates the objective from
your introduction and relates it to your results and discussion, and
describes any future experiments or improvements that you would
- Works Cited:
- A bibliography of all of the sources you got
information from in your report.
The title needs to describe what the experiment was about and give some
indication of what the procedure was. Remember that if people do an
internet search, the title is the only thing they will see, so a more
descriptive title is better.
Titles of lab reports are long-often almost a complete sentence
(except for the verb). An example of a good title might be "The Effect
of Temperature on the Pressure of Nitrogen Gas." Try to be as specific
as you can; "The Magnetic Properties of a Vanadium-Iron Alloy" is
better than "Properties of a Magnetic Alloy," or even worse, "Magnet
The title should not contain chemical symbols, formulas, or
abbreviations. Note that a separate title page is not necessary. Your
lab report is graded on content, not length, so there's no reason to
kill extra trees.
The abstract is a short (less than 200 word) "executive summary" of
your entire lab report. Its purpose is to communicate your entire
lab report (procedure, results, and discussion) to somebody who doesn't
have time to read it.
An abstract is like Spark's Notes for your lab report. For a high
school lab report, it will probably be one paragraph of 4-6 sentences.
The first 1-2 sentences should describe the objective of the experiment
and the procedure. (The description of the procedure should read a lot
like the "Experimental Plan" in your lab notebook.) The next 2-3
sentences should summarize the major results and conclusions, and the
last sentence should describe any possible sources of error, the percent
error (for a quantitative lab), and any other limitations or caveats on
Abstracts are often published separately from the rest of the report, so
your abstract must be complete and make sense without any of the rest of
your report. This means your abstract can't refer the reader to any
other section of the report for tables, figures, or other information.
This section describes the science behind your experiment, and should
tell the reader why you performed it. The introduction should include
background information about the chemical principles involved, and a
summary of any prior related experiments. If your experiment includes a
hypothesis, you would state it in the introduction.
For a high school lab report, the introduction should contain at least
two paragraphs. The final sentence of the last paragraph should state
the objective of your experiment, much like the final sentence of the
introduction section of a term paper usually states the thesis of the
The information in your introduction will almost certainly come from
other sources (textbooks, class notes, handouts, etc.). You need
to include citations that point to bibliography entries in your Works
Materials and Methods
This section (sometimes called "Experimental") describes your
procedure, in enough detail that someone else with your level of
experience could repeat the experiment. The section must be in
paragraph form, and in the past tense. e.g.,
Sodium carbonate (10.0 ml of a 0.10 m solution)
was placed in a 100 ml beaker and acetic acid (0.50 ml of a 1.0 m solution) was added.
You must include all of the relevant quantitative information, such as
the names and concentrations of all chemicals used, temperatures, times,
etc.) Your description must be specific. If the experiment
involves a complicated set-up, you may include a drawing to show it.
(Remember that figures need to be numbered and have titles, just like
tables.) However, the drawing is not a substitute for the description.
Be sure to include the manufacturer and model number of major laboratory
equipment used (pH meters, spectrophotometers, etc.)
The first time you mention a chemical, write out the name, followed by
the chemical formula in parentheses (e.g., sodium chloride
(NaCl)). After the first time, you can refer to the chemical by its
You may assume that anyone who is reading your lab report will know
basic chemistry. For example, don't bother to mention safety goggles,
but you should mention any unusual hazards or precautions,
including whether any of the chemicals are explosive, flammable, or
toxic, or if there are any special procedures for disposing of wastes.
Do this in a separate paragraph, starting with the word "Caution:".
If your procedure is based on a written procedure from another source
(such as a lab handout), remember to include a citation and a
bibliography entry in the works cited section.
In this section you present your data. You will probably want to use
tables and/or figures to present the results. However, every figure or
table must be numbered and the number must be mentioned within the text.
All figures and tables also need titles, and need to be labeled with
enough detail that someone who is not familiar with the experiment will
know what they represent. (Remember to include units in your tables,
and labels on both axes of your graphs.)
Keep in mind that tables are useful when the reader wants to know exact
values, and graphs are useful for showing trends and for deriving values
from a statistical fit of data. Tables and figures should be numbered
sequentially (such as "Table 1" or "Figure 1"), and each one should
have a descriptive title.
If your data include any calculated values, you must include the
formulas in this section.
The Discussion section is where you interpret and compare your results.
You should compare your results with published or theoretical values
(including percent error) whenever possible, and list and analyze
possible sources of error. (Remember that published values need a
citation in your works cited section.) If your experiment includes a
hypothesis, you need to evaluate how well your data support or refute
As with an English term paper, this section should start with a sentence
that restates and evaluates the objective that you stated in your
introduction. Then, give a brief summary of the main results and
conclusion(s) of the experiment (you'll probably use the same text here
and in your abstract), as well as restating any major problems or
sources of error. Finish with suggestions for improvements or future
Any information that came from another source (including your textbook,
class notes, handouts, etc.) must be listed here. You can
use the same format for references that you use in your English classes
or any other format, as long as it includes the author, title, where &
when the work was published, and the specific location within the source
(such as page numbers).
Lab reports must:
- be typed or typeset on a computer, except for diagrams, which
may be handwritten as long as they are neat and legible.
- include your name, and the name(s) of your lab partners (even
though each of you must turn in separate lab reports).
- include your teacher's name and the class period.
No First- or Second-Person Pronouns
In formal writing, including lab reports, never use the first or second
person. Instead of saying "I dissolved 8.5 g of sodium chloride in
100 ml of water," or worse yet, "You dissolve 8.5 g of sodium
chloride in 100 ml of water," you should say, "Sodium
chloride (8.5 g) was dissolved in 100 ml of water."
You have probably been told to avoid the passive voice by your English
teachers. (The previous sentence is an example of the passive voice;
the active version would say, "Your English teachers have probably told
you to avoid the passive voice.") However, scientists often use the
passive voice, particularly when describing experimental protocols.
This is done intentionally, to emphasize the fact that the report is
about the experiment and its results. To your readers, the experiment
is what matters; you are irrelevant! For example, most chemists would
write, "The solution was heated to 100°C for 25 minutes,"
rather than "the investigators heated the solution to 100°C for 25 minutes."
Lab reports are written in a combination of past and present tense,
depending what you are writing about. If you are writing about things
you did (actions that took place in the past), such as the details of
your procedure and the results that you observed, use the past tense.
However, use the present tense for trends and properties. For example,
write "The solution was heated to 100°C for 25 minutes."
because that was a specific action that was carried out at a specific
time in the past. However, write "ammonia and hydrochloric acid react
to produce ammonium chloride gas", because this happens every time
these chemicals come into contact with each other.
Numbers at the Beginning of Sentences
Never start a sentence with a numeral. (The figure "2" is a numeral;
the word "two" is not.) However, you need to report all numbers to
the correct number of significant figures. This creates a problem: if
you added exactly 1.00 g of salicylic acid to a beaker, you can't say
"1.00 g salicylic acid was added..." because you can't start a
sentence with a numeral. However, you also can't say "One gram of
salicylic acid was added..." because you need three significant
figures. You also can't say "I added 1.00 g of salicylic acid..."
because you can't use the the first person. The solution is to start
with the substance, and put the exact amount in parentheses, e.g.,
"Salicylic acid (1.00 g) was added..."
Other than the above, you should follow the same rules of formal English
grammar and usage that you have been taught in English class. Note
particularly that the word "data" is plural, so you need a plural verb
with it. You can't say "The data shows that..." This is as bad as
saying "The people says that..." If you ever need to use the
singular of data, it's "datum".
Simpson, Bill. Laboratory Report Style.
(accessed June 2004)
Queeney, Kate. Guidelines for Writing a Formal Laboratory
(accessed June 2004)
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