April 20, 2004
How to Write a Good, if not Perfect Lab Notebook
Ashley Carter - Advanced Optics Lab
Why are good lab notebooks important?
A complete, legible, thorough lab notebook allows anyone to be able to perform
the experiment you have done, even yourself! For example, Dave Samuels, a chemistry
student who went to Japan for an internship at Sony, used his lab notebook to setup a
Mach-Zender interferometer1. With his background in chemistry he said that it would
have been very difficult to setup that system without having the advanced optics lab. In
such a case, it is essential that your lab notebooks contain all of the pertinent information
about the experiment you have done. That way at a later date you or somebody else can
easily reproduce your work.
Furthermore, keeping a good lab notebook is a good habit to get into. If your
actual lab notebook contains illegible experimental data or is incomplete then it will be
hard to publish papers or patent devices. To prove this point I would like to relate two
anecdotes about very bad notebooks. The first is about LeMonnier, a French astronomer
that actually discovered the planet Uranus. His notebook was so incomplete that he
concluded that Uranus was a comet, and instead someone else (Herschel) is credited with
the discovery. The second is about Gordon Gould who did some interesting work on the
uses of lasers when they were first being developed. Sadly, he had his notebook
witnessed by a candy store notary and didn’t document private communications. As a
result he had several legal battles before he was awarded some of the credit for his work2.
The lesson of both stories is that good lab notebooks are important.
How should I organize my lab notebook?
The first thing that a good lab notebook should have is organization. There
should be a table of contents on the first page with all of the labs/prelabs referenced. At
the top of each lab/prelab should be the title of the experiment, the date, and the names of
any collaborators. Then each section of the lab/prelab should have the question pasted in
the notebook at the beginning of the section and should be followed by the experimental
setup, data, results, and conclusions. Other variations are possible, but a reasonable
organization of the lab notebook will allow the reader to scan to find the desired
measurements.
For each lab section (or new experiment) there should be an experimental diagram
and procedure. First you should build the experiment for that section and verify that it
works. If it does then you should draw a diagram of it. Label all of the distances and
objects. Make sure that variable object parameters like focal lengths, pinhole sizes,
magnifications, etc. are recorded. To make drawing the diagram easier you may want to
develop a series of symbols for commonly used objects and just have a key. Other
objects you can represent with a square and identifying initials. Please see Figure 1A for
an example of a good experimental diagram. After the diagram you should write down
any procedures or helpful hints that weren’t in the lab question that you taped into your
notebook. Don’t assume anything is obvious, because usually it isn’t.
April 20, 2004
After the experiment is built and diagramed you should relate the outcome. The
outcome could be a picture, an observation, or a table of data points. A picture should be
titled and labeled. Plus any generalities should be noted. See Figure 2 for a properly
drawn picture. An observation should be clearly stated. Tables of data points should be
labeled appropriately with the right units and titled. Also the error in the data should be
noted.
Finally, any outcome should be analyzed immediately after it was observed to
make sure that you are seeing what you expect. Analysis may mean to draw a graph or
calculate some value. For a graph make sure that there is a title, the axis are labeled
properly, and the data points are shown as is the case in Figure 1C. For calculating a
value, make sure that the calculation is referenced or clearly written in your lab notebook
with all of the steps. Also make sure to solve in terms of variables and not plug in actual
numbers until the end. After the graph or calculation be sure to note any errors that might
have propagated through your measurement. Then box any value or observation that
answers the questions asked by the lab. Lastly make sure to compare your answers to
what you expect. Don’t say that the answer is “close,” it is either within the error (and
therefore what you expect) or not3. If the answer is not what you expect you may need to
do the section over, or at least explain what other errors could have caused the faulty
measurement. Don’t lie about your data to get an answer you think is correct. It is much
better to be honest and relate what you saw. As long as someone can follow your lab
notebook and produce the same result, then you are not wrong according to your
procedure.
How can I make my lab notebook better than good?
Keeping a good lab notebook is easier if you have the right tools. A notebook
with page numbers is a must. Quadrille ruled is also nice so that it is easier to draw
pictures, tables, and graphs. A larger notebook with pages big enough so that 8.5”x11”
pieces of paper can be taped into it is very convenient as well. Plus the notebook should
be labeled with your name, phone number, address, or anything that would identify it as
yours should it get lost. A pen must be used, not pencil. This will prevent smudging and
any urge to erase. A ballpoint pen is usually the best, since felt tip pens tend to bleed or
smear and can become very messy.
Lab notebooks are much better if you do everything in the section at once.
Sometimes you might want to put something off until the end, or do something at home.
This is good in theory, but usually if you don’t write anything down for a section,
chances are you will remember less later. Plus as the lab progresses you will get more
tired, so that putting things off until the end, becomes not doing things at all. Another
reason is that sometimes lab sections build on each other so that if you don’t have one
section completed, it is harder to do the next section.
The other way to improve your lab notebook is to ask the TA or professor
questions. This especially helps if lab questions are open ended or aren’t clear. The TA
or professor can tell you what they were expecting when they wrote the question.
However, make sure to write down any assumptions that you make about what the
question is asking for later use. Plus, the TA or professor can tell you other exciting
things to look for that might not be explicitly written in the lab question. Also, they can
April 20, 2004
give you hints for the best or fastest way to setup the experiment for each section. This
can improve your results or at least increase the amount of time you are able to spend
exploring.
Probably the most beneficial advice is what to do if you make a mistake. If that
happens then just cross through the mistake once so that it is still visible, and don’t erase,
white it out, or obliterate it. Mistakes are results too and you want to be able to look back
and see that you made them4. If you made an error and there is not enough room to fix it,
then write down a reference to another page where there is enough room to fix the
mistake. Also make sure that before the correction you note that it is a correction from
whatever page, and that after the correction you write down that you are continuing from
whatever page. Do not rip out, or add pages to fix mistakes, or in general3. Remember
what R. Coueto said, “It is a notebook, not a neat book2.” You will make mistakes so that
your lab notebook is not perfect, but these are to be expected and actually add more than
they detract from the notebook.
How do I keep a legible notebook?
Although your lab notebook doesn’t have to be pristine, it does have to be legible
and reproducible, so some level of neatness is required. This is especially painful for
people that are bad at drawings or handwriting. To correct bad drawings use a straight
edge, protractor, or grid lines whenever possible. For bad handwriting write more and
make your words bigger. If you write bigger, it is easier to see in general and letters are
wider spaced for easier determination. If you don’t use abbreviations or short phrases
then it will be easier to determine the word from the context clues. Compare the three
writing samples in Figure 3. Notice that the bigger and wordier samples are the easiest to
read. For both of these problems and neater lab notebooks in general it helps if there is
lots of white space. White space can be used to break up sections and also different parts
within sections. Plus if things need to be added later, then there is always room to add
them.
A neat lab notebook is easily accomplished with the aid of computers. If there is
a nearby computer that is able to print then it is much easier to have a neater notebook.
Graphs can be plotted on a computer, printed out, and taped into the notebook.
Oscilloscopes that have printers can print out a trace which can be taped into the
notebook (make sure the tape doesn’t cover any data because the ink on the trace may be
dissolved where the tape is). The digital camera can take pictures of optical phenomenon
which also can be printed and taped in. Plus, for students with really bad handwriting a
section summary can be typed up quickly and pasted in for a neater notebook. However,
this all depends on having a computer, oscilloscope, or digital camera that works. This is
not always the case so depending on these devices is not a good idea.
Awknowledgements
The author would like to thank Marty Boyd for his input on how to overcome bad
handwriting, as well as Bob McLeod, Carol Cogswell, and Ed McKenna for their
evaluations of my labs. This paper was done as a part of the Advanced Optics Lab class
at University of Colorado. Tuition was funded by OSEP.
April 20, 2004
1
private communiqué with Dave Samuels
http://www.macro.lsu.edu/howto/Lab%20Notebooks.ppt
3
http://physics.ubc.ca/~phys209/pics/good_writeup
4
http://academic.reed.edu/writing/disciplines/lab_notebook.html
2
April 20, 2004
Figure 1A: This is a lab notebook excerpt from the crystal optics lab where a student observes what
happens when a half waveplate is rotated. Comments in red indicate good and bad observations about
the lab notebook techniques.
Setup contains measurements and a
legend
Good procedure for
alignment of the setup
April 20, 2004
Figure 1B: Continuation of Figure 1.
Don’t scribble out just
cross out once
Show error in measurements
Good to show calculations for
columns in table
Good to graph as you go
so you know if data
looks good, in this case
the ½ waveplate was
clipping so need to
retake data
April 20, 2004
Figure 1C: Continuation of Figure 1.
Now data looks
better
Always
comment on
trends of
graphs and
possible
errors
April 20, 2004
Figure 1D: Continuation of Figure 1.
Compare
what you
got to what
you expect
April 20, 2004
Figure 2: This is an example of a good picture from an excerpt of a lab notebook on the crystal optics
lab. The student draws very detailed pictures of what the output beam from a conscopic crystal setup
looks like. The student titles and labels each drawing and provides measurements. In the text “P2”
refers to the second polarizer.
April 20, 2004
Figure 3: Example of bad hand writing from a lab notebook on the crystal optics lab. The
student is trying to explain what limits the isolation of back reflections off of a mirror when
two polarizers and a quarter waveplate are used to eliminate them. In the first paragraph the
student writes too small and the text is illegible. In the second paragraph the text is still
small, but the student writes more so that the reader can tell from context clues what is
being said. In the third paragraph the student writes bigger so that the text becomes legible.