HOW TO WRITE A FORMAL LAB REPORT
The writing of a laboratory report will help you to understand the theory in the course much
better. It will require effort, neatness, and patience on your part. However, when you are
finished, you will be a better person.
Each lab you do may contain the following...
TITLE: Include lab number, your name, and the date performed.
INTRODUCTION: The introduction of a lab is not very different from the introductory
paragraph in a novel or essay. It brings an unfamiliar reader into contact
with the essential elements of the subject at hand.
The introduction could: 1. Identify your variables and how they are to be
measured.
2. State what you hope to learn.
3. Introduce and define any new terms.
The introduction may also include some initial, rough experimentation and
observation.
Example: “Any thoughtful observer who has seen grass wilting by the roadside after salt
has been spread or a plant perking up after a summer shower may wonder why
water and salt both have an effect on plants. Is there a common reason why
both salt and water affect plants? This laboratory investigation will explore
the phenomenon of osmosis – water movement across a semi-permeable
membrane – and explore the effect of the concentration of the surrounding
solution on plant cells.”
PURPOSE: This is a single succinct statement of what you are going to do. (You may quote
directly from the lab manual if you wish.)
Example: “To determine the concentration of solute of potato cell cytoplasm.”
PROCEDURE: This is a step by step description of how the experiment was carried out. As far
as I'm concerned you may quote the manual as long as you note any changes
you may have made.
Example: “As in Lunn et al., Investigations in Biology, 2d ed., pp. 39 - 41; except that
our study used ten extra solute concentrations at increments of 0.05 moles/L.”
RESULTS: This is the raw data which has been collected. Use tabular form wherever possible.
E.g. Data Table: Effect of solute concentration on potato samples
Test tube #
[Solute]
Initial mass
Final mass
Change in mass
mol/L
(g)
(g)
(g)
2
0.95
20
…
1.00
…
1
% change in mass
0.00
ANALYSIS OF THE DATA: This makes up a large bulk of the lab, where you attempt to figure
out what the data means. Here you answer questions from the lab
manual, draw graphs, and include calculated data tables.
Please have this section neat and presented in a logical order.
Also, refer to your graphs in the written text of your analysis.
Don't just stuff them in at the back without referring to them!
CONCLUSION: This section answers to your introduction. Questions or predictions from the
“Purpose” should be answered. State what you have learned. Compare your
results against theoretical results, if applicable. Summarize the lab.
SOURCES OF ERROR: In some experiments there is no significant source of error so you may
leave this section out.
Otherwise, mention only those sources of error which are unavoidable
and significant. For example, you may have had trouble immersing the
potato sections in the liquids or you may have noted a certain degree
of error as you computed the slopes of freehand drawn graphs.
Do not, under any circumstances, include human bungling or errors
which you have corrected.
What we are after are flaws in the design of the experiment and ways in
which the experiment could be improved.