The Do's & Don'ts of Lab Reports (McGill SUS Peer Tutoring)
The Elements Of A Good Lab Report
3) Materials and Methods
7) Supporting Information
What is the purpose of a lab
Enhance understanding of the material being
Ensure that all aspects of the lab were done
with ultimate precision
Communicate scientific results and ideas in a
Prepare for research paper writing
How does this apply to
You are being taught to write a lab report without
Each piece of information you write for this lab
corresponds to a section of a formal lab report.
You will most certainly have to write a formal lab
report in your academic career.
What is a good title?
Make the title specific
A good title tells the reader what the report
will be about
Does not necessarily give the conclusions
Keep the title short: <10 words
Can be written last
What is a good title?
✗ Use “Lab Report 1”
✗ Use abbreviations
✗ Don’t be wordy
“The soda’s effect on the height of explosion
on the addition of a Mentos” ✔
“The effect of Mentos on soda” ✗
BRIEF summary of what experiments were
performed, the main results and conclusions.
“A mini version of your lab report”
Should contain one sentence for each section of
your lab report
Shorter than 200 words.
✗ Don’t make it too detailed
✗ Don’t have more than one paragraph
✗ Don’t use too many technical words
Anyone with a background in this field must
be able to understand it
Four main sections:
Purpose and objectives
Significance of the performed experiment
Enough background information to
understand the report
Write this section first
It simplifies writing the rest of the report
✗ Explain materials and methods
✗ State any results or conclusions
✗ Leave out important background
information, even if it’s the lab manual.
What is a good hypothesis?
Not a guess: it’s an educated guess!
Tentative explanation for an observation, phenomenon or
It can be tested experimentally
Do use the “If … then…” format
“If the type of soda is changed to Dr. Pepper, then the height of
the reaction between the soda and mint Mentos will increase.”
“I think that Dr. Pepper will have the highest fountain.”
Don’t write it at the end
Materials and Methods
Provide enough information for another scientist to
repeat your work
Describe the following in a general manner:
How solutions/samples were obtained or prepared
How were they used in analysis
Amount(s) of substance(s) (including molar quantity)
Volume and concentrations of solutions
Refer to your lab notebook to write this section
Materials and Methods
✗ Be overly detailed
“We measured the mass of the test tube by first calibrating the
scale by pressing the zero button and then placing the tube on
the round metal part.” ✗
“The test tube was weighed” ✔
✗ Copy the procedure given in the lab manual
✗ Don’t include your results
✗ Don’t forget to write the method in past tense!
In the Lab - Data Collection
Your data is collected and signed by your TA during
the lab, you CANNOT change it later on
1. Be prepared: you should know what is a
“reasonable” value to obtain and how to obtain
them with proper techniques.
1. Be alert: if you see something is off by a magnitude,
you know you need to do something.
Good data = easy discussion = easy lab report!
Remember to hand a copy of your data before you
leave the lab!
Present your data here
Present everything in a logical order
Follow your Methods section
There are 2 main elements for this section:
Number all tables and figures!
✗ Do not discuss the results
Results – Hints on Writing Style
Explain every table and graph with proper title
and explanations under it if necessary
Use past tense
Be objective and impersonal: passive voice is
dominant, but use active voice as much as
possible for clarity
Make sure to organize your results in relevancy of
how you will discuss them
What is a good figure?
• Descriptive Title
• Each figure should be
• Axis labeled -> Units!!
• Easy to understand
Volume NaOH added (mL)
What’s wrong with this figure?
1. Scale missing on the x-axis
2. Very poor title
3. Figure not numbered
What’s good about this figure?
1. The units are written out
2. The figure is easy to read
What is a good table?
Hint: keep your units consistent throughout the report
It is important for easy understanding of calculations and later
arguments in discussion
• Data should be presented in tables
• Should be numbered
• Descriptive title
• Each column should have a label and unit
Moles of Water (mol) Mass
Table 1. Mass of Water
What’s good about this table?
1. The figure is easy to read
2. The table is numbered
What’s wrong with this table?
1. Missing some units
2. Non descriptive column
3. Very poor title
The most interesting and important part of your lab
Must be original
A good discussion should include:
How your data correlates to the greater concept in
What you did wrong/why your results may vary from a
SOME COURSES MAKE YOU MENTION EXPERIMENTAL
ERROR! (% value)
Discussion – Logical Order
Your interpretation of results and degree of your
experiment answered your questions
Alternatives of your design and mean source of
Give your conclusion and it’s significance
Busts of Your Discussion Section
Do NOT say the following, even if it happened:
1. I knocked over my flask and some of the material
inside was lost.
2. Human error: I do not know how to use…
3. The machine is old
4. There was not enough time to carry out all parts
Something went wrong…
Mention it in your discussion!
People do not have perfect results all the time
These reasons can be considered:
1. Experimental design: Can the measurements be made
differently to eliminate some of the error?
2. Mean source of error: These are things you cannot control
(open environment, possible loss due to evaporation, etc)
3. If you had not made a mistake, what would be the error ?
Should be 2-3 sentences long
Indicate what the experiment was about
Outline the main method of the experiment was
done (ie, was it done via titration?)
Technique for improving results for next
✗ Do not summarize results, give
implication of meaning of your results
✗ Do not deviate from your objective of
experiments – i.e answer the question
Check what kind of style is required for lab reports
If you manage references manually, follow the
guideline EXACTLY. (Not recommended)
Refworks, EndNote are both reference management
Automatically handle the references for a lab report or a
McGill library offers seminars teaching how to use them
Not normally required for a lab report
Anything that doesn’t belong in a specific place
can be put as supporting information
Scientific related information ONLY, no personal
notes to grader
Details of experiments for publishing in certain
journals that have page limit for papers
…Some Final Words
Do not hesitate to contact you TA if the
requirements are not clear!
Nothing worse than losing points for format or
required samples calculations, figures etc.
DO NOT PLAGIARIZE!
You may feel you are smart enough to get away
with it – DON’T DO IT!
Start writing the report EARLY!
Lab report writing is time-consuming: more than
you expect usually.
Happy lab report writing!
Please do not be shy to ask
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