How to write a lab report that will earn you a good mark and
prevent your TA from going insane
October 7, 2009
Many students are unsure of what constitutes a top-quality lab report. With that in mind, I have
prepared a list of tips and common mistakes broken down according to the sections of a typical lab report.
First of all, DO NOT PLAGIARIZE. If you copy off your partner, I can tell. If you copy off Wikipedia,
I can tell. Bottom line: don’t do it. You’ll get busted. If you borrow information from a book or online
reference, you must cite the source. Grab any physics journal from the library or online (http://arxiv.org is
a great source) and have a look at a few articles to see how to properly credit other authors.
One of the most important factors to remember is neatness. This counts a lot more than you might
think. Hastily scribbled calculations, incomprehensible figures and disorganized or missing data tables make
your TA very annoyed. An annoyed TA is more likely to mark your report harshly, whereas a neatly written
report will put your TA in a good mood, which often translates into a better mark!
Most importantly, LISTEN to your TAs in the lab and READ THE MANUAL, including the appendices.
These sources will provide all the information you need to do the experiment and write the report.
• Don’t just copy it out of the manual, or you will get 0 for this section. Explain in a sentence or two
the objective and how you will accomplish it. No need to repeat the entire procedure; just highlight
the tools, measurements, calculations, etc. that you used. For example: “Objective: To use a prism
spectrometer and sodium and mercury light sources to determine the index of refraction of a prism,
to identify the type of glass of which the prism is made, and to determine its resolving and dispersive
powers.” It’s that simple!
• Include a diagram (done neatly by hand) and clearly label all important components. Figures should
be large enough to clearly identify the components. If you are using a numbered sample (prism # 1,
e.g.), make sure to identify it, since the TA might need to verify your results.
3 Theory (formal reports only)
• Explain briefly the physical principles you are investigating.
• Don’t just write down a bunch of equations! Explain them! What are the variables? What does the
result mean? Why is each equation relevant to the experiment?
4 Data & Calculations
• Make sure your TA initials your rough data before you leave the lab. This is the only way I can be
sure that your data is your own. If the signed, raw data isn’t in your lab book, I’m going to be awfully
suspicious. This does not bode well for you.
• Every measurement and calculated result MUST have an uncertainty. Make sure to include the correct
number of significant figures in the uncertainty. Refer to your manuals if you are not sure how to
• Data and calculations should appear in the report in the same order in which they were performed. If,
for some reason, this is not possible, make a note referring to the appropriate page so the TA doesn’t
have to go hunting for the missing work.
• Calculations should be neatly organized, with the results clearly indicated (highlighting or drawing a
box around the final result works very well). Take the time to recopy your data tables and calculations
neatly instead of just handing in your rough notes by themselves. A sentence here and there to explain
what you’re doing can be very helpful. The final results of your calculations should be displayed neatly
in a table. All tables must have titles. See the examples in your manual.
• Graphs should be big. BIG. Go on, use the entire page! All graphs must have titles, axis labels, slopes
(if applicable) and units. See the examples in your manual.
• DO NOT say things like “This was an interesting lab and I learned a lot about...” or “This experiment
was a success.” This is guaranteed to make your TA’s head explode.
• Instead, discuss the physical significance of your results. Do they make sense? (Hint: statistical analysis
can be useful here. See your manual.) Say, for example, your prism has a ∆λ value of 0.28 nm. What
does this mean? How does it influence your other results?
• Try to determine which uncertainties or sources of error had the greatest impact on your results. Hint:
It’s not human error, nor is it the fact that you believe your partner to be a moron. These are two
more “lab report greatest hits” that will make the TA’s head explode.
• Is there any way to reduce the uncertainty on your results? Can you think of a better experimental
setup, measuring technique or analytical method that would improve the lab? (Be reasonable - we
don’t have access to an atomic clock, for example, and even if we did, you probably wouldn’t be allowed
to touch it.)
• In a few lines, sum up the results of the experiment. Did you confirm some hypothesis or law?
7 A few last words
What’s the most important point to take away from all this (other than the fact that your TA has far too
much to say)? Be thorough in everything that you do in the lab. Physics is all about understanding how the
universe works, down to the finest details. If you ignore the details by being careless in your measurements
or your analysis, you cannot expect to obtain good results. However, if you take the time to fine-tune
your experimental technique and perform the necessary calculations and analysis, you will find that you will
receive better marks on your lab reports - and you might just learn something along the way.