Our AP Biology lab activities are designed to provide a wide variety of
experiences. They will fall into two general categories:
or "skill" labs, and " experimental labs.” "Observational
will mainly involve watching or observing natural phenomena occur or
some scientific technique, while "experimental labs" will involve
process skills, such as hypothesis formation, manipulation of
gathering, tabulating and graphically displaying data, etc. In college,
report requirements vary greatly. Some are quite rigorous and require
a review of the pertinent scientific literature be included in the
Since we are greatly limited by time in this course, our write-ups will
brief and less rigorous than ones that you may do in college.
It is essential that you prepare for labs before coming to class.
You will be required to keep a lab notebook in which you will write
prelabs, record data, and note any conclusions or thoughts that you
have as you perform each lab. At the beginning of class on lab
days, prelabs will be checked. The following components should be
1. Title and date of the lab
2. Purpose - 1-2 sentences describing the
major goal of the experiment
3. Procedure - an easy to follow numbered list
of steps that will be performed in the lab,
written in your own words.
For labs with several parts, divide your procedure accordingly.
You may wish to sketch diagrams to help you
visualize the steps of the lab. Once you are
done, you should be able to do your lab report
without consulting with the lab book.
4. List the following: independent and
dependent variables, control and experimental groups, constants, and
5. Data - As you write your prelab, create all
the data tables you will need. Read the procedure
carefully to determine all the information you will
be recording, and organize it neatly. Remember to include units
at the top of each column.
During the lab
1. Fill in your data tables.
2. Note any changes that you make to the
3. Conclusions - Leave a space where you can
jot down notes and other thoughts during the lab.
This will help you to write your lab report later.
After the lab
Lab reports are due two days after the completion of the lab in
class. This gives you enough time to ask any questions about the
lab or get help with concepts you don’t understand. Lab reports
must be typed, handwritten work will not be accepted (exception:
data tables and graphs may be done by neatly hand). 1/2 credit
will be given to lab reports that are
late, up to 24 hours. Remember that if you are tardy to class the
any assignment is due, your assignment will be counted late.
hours, reports will not be accepted. Keep all returned lab
reports. Labs constitute a significant portion of the AP exams.
Title: This should indicate what the
lab is all about. Be brief, but indicate the nature of the
investigation. What was the specific question being investigated?
Specifically, what was being observed ? Please do not exceed 25 words.
Tips for writing titles:
- All experimental labs should follow this format: "The
Effect of ______ on _________.
- Be concise. (Instead of, “environmental stimuli such
as light and moisture” write, “light and moisture”).
- Always list the specific variables you tested.
- Include the scientific name of organisms involved.
Methods: What procedures were followed,
what purposes did they serve,
and what materials and equipment were used? For experimental labs
and AP Labs, be sure to identify the independent and dependent
variables, the constants, and the control group. For observational labs
explain what you did. Never use personal pronouns. Do not create
a list of materials, just include them within the context of your
Tips for writing methods:
- At the beginning of your procedure, explain the ‘big picture’ of
the lab. Explain what biological processes we are trying to learn
If the lab has several sections, revisit this in each section.
relevant vocabulary terms in a way that demonstrates your knowledge.
- Write in the past tense. Your purpose is to communicate
what you’ve done, not give someone directions.
- Use the impersonal tense. (Instead of, “We made
choice chambers. .“ write, “Choice chambers were made. . “).
- Explain how data were gathered.
- Include your hypothesis, and briefly explain your reasoning.
- When writing your hypothesis, be as specific as possible about
what you are measuring.
- Ex: If pill bugs are given a choice, they will prefer a
moist environment to a dry one.
- Better: If pill bugs are placed in a choice chamber, more
will be found on the moist side than on the dry side at any given
- If you performed any statistical analysis, including calculating
an average, this should be in your procedure.
- Include the scientific name of the organism you are testing, and
how you obtained your specimens.
Results: This part of the report will
display, in table form and with a proper title, the data that you
collected. It should also include any
graphs labeled properly and in proper graph form. It should be neatly
clearly presented. If the lab is "observational" in nature, you should
diagrams and/or descriptions of structures (labeled as instructed),
reactions, behaviors, etc. DO NOT FUDGE YOUR DATA!! Put only the data
you, or your lab group, or the class collected, not what you think that
should have seen. Use graph paper to graphically display your data
Tips for writing results:
- 1 experiment = 1 table. Don’t do a separate table for each
- Keep an entire table on 1 page (don’t split it over 2 pages).
- Always include a column for averages. Units for an average
are the same as for the trials.
- Use a consistent number of digits. (Don’t put “5” in some
places and “5.75” in others. Use “5.00”). Pay attention to
- Organize your data. If you have to write the same thing
several times, you need to restructure.
- Give tables a number and a title (be consistent throughout the
report) so you can refer to them in your discussion.
Table 2: Number of pill
bugs in the acidic choice chamber
- Ex: Table 1: Number of pill bugs in the wet
Figure 2: Pill
bug (side view)
- Give figures a number and a title, too. Figures are any
kind of drawing or picture, and graphs.
- Ex: Figure 1: Pill bug (top view)
3: Average number of pill bugs present in wet choice chamber
above example, the first 2 figures are drawings, the third is a graph.)
- When graphing your data, only graph the average values of your
trials, not the data from every trial. (Often, the reason why
several trials are done is so we can average them and reduce error).
- Be sure to label your axes and include relevant units. If
necessary, include a key.
Discussion: Here you present a summary
of the data generated by the lab. Put into your own words what the
numbers or observations tell you. How do you interpret the data or
observations in light of your hypothesis or your own expectations? Do
not make the mistake of looking for the "right answer" and please do
not ask, "what was supposed to happen?" Nature does not lie, but is
often frustratingly difficult to figure out. In this section you must
discuss YOUR results. If you come up with results that do not make
sense, examine your methods and materials for sources of experimental
error and describe them here. For purely observational exercises, your
discussion should include reactions to what you have just done and
learned. Additionally, error should be thoroughly discussed. This is,
perhaps, the most important part of the lab discussion. Your discussion
of error will help the reader decide whether or not your experiment is
valid or invalid. Note: for our purposes
in this class, measurement errors are not acceptable because this could
used as an excuse on every lab, and does not that you are thinking on
the design or execution of this experiment could be improved. It is
by your instructor that measurements were take accurately.
Tips for writing discussions:
- Refer to your tables and figures and explain important
findings. Use your data to support your statements.
- Only use the word “significant” if you’ve done a statistical
analysis. (Significant means something different to scientists
than it does in a nonscientific sense).
- Your hypotheses can be “supported” or “not supported” by the
data, they cannot be “proved” or “disproved.”
- Use the impersonal tense. (Rather than “We believe . . . ,”
write, “It was found. . . .”).
- Always be as specific as you possibly can be. (Instead of
“Most of the time . . . ,” write “For 7 of the 10 time intervals
. . .”).
- Don’t describe your data as “vague” or “inconclusive.” If
a trend that you thought would exist, doesn’t, that doesn’t mean the
are vague. The absence of evidence is not evidence of absence.
- When describing sources of error, don’t include irregularities in
the environment that you controlled. (Ex: The
florescent lights in our room affect your control group the same as
your experimental group, because they are on the whole time.
Therefore, they’re not a source of error. This is why we do a
control in the first place!)
- Always be exact in your terminology. (Ex: “dry choice
chamber” is better than “dry environment”).
- Be sure you have a complete understanding of terms before you use
them. (Ex: Concluding that pill bug behavior is a taxis
because it was a ‘response to a stimulus’ is incorrect.
Kinesis is also a response to a stimulus, its a random response rather
than a directed one).
- Be grammatically correct with your use of the word “data.”
“Data” is the plural of “datum.” (If your not sure, substitute
“numbers” instead of data. Instead of, “This data shows. .“
“These data show . . “).
- Whenever trying to explain a behavior or an adaptation, it may
help to look at it from a natural selection perspective.
(Think: How is it an advantage to the pill bugs survival and/or
reproduction to find a moist environment?)
- Be aware of what you are measuring. (A pill bug’s
‘preferences,’ ‘desires,’ or ‘needs,’ are not measurable. Its
movement, or its presence in a certain choice chamber, is measurable).
Analysis questions: In this
section, put the answers to ALL questions asked within the lab, and at
the end of the lab. Answers should be given in
complete sentences. Remember, the write-up is due 2 days after
are completed in class.
NOTE: YOU WILL HAVE EXAMS ON LABS. There will be stations
or video slides that cover the material. Don't waste lab time or you
will be given less time to do them!!!!!!!!