The Laboratory Notebook
AP Biology
The laboratory notebook is an essential part of scientific research. It is a complete
record of the experiment being conducted. For successful experiments, it allows other
scientists to repeat and confirm your findings. For unsuccessful experiments (by far the vast
majority), it allows for a post-mortem evaluation, identifying mistakes by the researcher,
inadequacies in the equipment, or incompleteness in the protocol. In industrial and
commercial labs, it also serves as a record of when discoveries are made, which is very
important in patent applications.
You will be using a college-style bound lab notebook. While your lab notebook will
follow traditional conventions, you will have some flexibility to develop your own style of data
recoding. You must ensure your notebook is organized, clear, and able to be followed by other
trained scientists. A guide to completing the notebook follows, including a sample notebook
page.
Some general notes—
Read the lab completely before you even touch your notebook. Pay attention to the
purpose of the lab (what you must experimentally determine), the technique you will use to do
the lab, and what data you will amass. You should plan any data tables you will need.
Always use pen when writing in your lab notebook. Make sure the ink is not water
soluble, or spills could eradicate your data.
The entries do not have to follow a set form. Some researchers use complete
sentences, others only phrases. Some write in paragraphs, others in bulleted or numbered lists.
Choose whatever form is most comfortable for you.
Below is information on preparing particular parts of the notebook entry:
Page Heading
The first page should include the name, date, and title of the experiment or experiment
part. Some of the AP Biology labs are actually a number of unrelated experiments. It is often
easier to enter these separately in your notebook.
Additional pages should include your name, date and a brief running title of the
experiment.
Purpose
At the start of each lab or section of a lab, write a brief purpose. It should be very
explicit: most experiments are designed to determine only one outcome. For example, you
may be placing a number of potato cores into many different beakers of varying concentrations
of sucrose and measuring the change in mass of the potatoes, but your goal is to determine the
water potential of a potato cell.
Procedure and Data
Since you will be repeating experiments done before and not designing your own
protocols, you should always start this section with a reference to the procedure you will be
following. Often this is as simple as saying “Performed experiment according to the protocol
from AP Biology lab 12.” In addition, briefly describe the steps you follow as you do them. A
numbered list or bullet list works well here.
Record all measurements and data in your notebook after the step you obtained them
or in a prepared data table if you think that more appropriate. Individual measurements are
best recorded in line with the procedure in your notebook. Recurring measurements are best
recorded in a data table. Always include the units, and pay attention to significant figures.
Always record the entire measurement from a device, even trailing zeros (e.g., 2.30 grams, not
2.3 grams).
If you perform a calculation in any of the steps, record it—even if it seems trivial.
Include the substituted formula and the answer you derived. Many scientists discover that
their experiment failed because of a simple mathematical error like using the wrong molecular
mass for a chemical when calculating a molarity.
If something accidental or unexpected happens, enter it in your notebook. If you
accidentally expose your chloroplast samples to light or if the solution that started out clear
suddenly becomes cloudy or colored, record it. The change observation or procedure mistake
may offer an explanation if your experimental results differ from the norm.
Do all work, including graphing, directly in the lab notebook. If you have a printout from
a piece of equipment, tape this into the notebook.
Conclusion
At the end of each lab or lab section, explicitly state your conclusion. This is often just a
few sentences long. Include numerical data to support your results. Though unfortunate,
sometimes you must state that you are unable to draw a conclusion at this time due to a
catastrophic failure in the experiment.