How to Write Your IB Lab Reports
During the year some labs or parts of labs will be graded for IB according to the
rubric given to you, in a number of different sections (Design, etc.). Not every lab is
graded for each area. For example, I might grade a particular lab report for just Data
Collection and Processing or for just Conclusion and Evaluation. Your ultimate IB grade
for Chemistry reflects the quality of your lab reports, the Group 4 project, as well as your
grade on the IB Chemistry test which you take in May. Your IB labs will also count
toward your El Paso ISD grade in this class. Though you may need to work with others
while conducting these labs in class, all lab writeups must be done entirely
independently and must reflect your own work only. I will have you sign an honor
pledge on this.
Your lab reports should include the following sections. Please keep this paper, as
well as the grading rubric, and refer to them when you write your lab reports.
Introduction – Clearly state the problem or research question. What is the purpose of
this lab? Provide some background information. Be sure to clearly state your hypothesis
and explain why you predicted what you did. Give support for your hypothesis.
Information from your textbook or other sources can be helpful here, though it is not
always necessary. You will also need to state your independent, dependent, and
controlled variables here. The independent variable is the factor you are manipulating in
the experiment. For example, let’s say that I asked you to design and conduct an
experiment testing the effect of a factor on the growth of plants. Suppose that you chose
to see how salinity of water influences plant growth. Salinity of water would be your
independent variable. Your dependent variable is what you expect to see change in
response to your independent variable. In this case, plant growth would be your
dependent variable. All other variables should be controlled, such as type of plant, soil,
amount of light, volume of water, etc..
Procedure – Describe your procedure in detail. This is best done in list or outline form.
Be specific about equipment used, amounts and concentrations of any chemicals used,
and so on. Keep in mind that your procedure should produce a controlled experiment. If
your experiment involves any complex apparatus or setup, it is very helpful to include a
drawing of it in your lab report. In general, a minimum of five trials is needed for an
experiment. I am aware that time constraints do not always allow you to conduct five
trials.
Results – Present your data here. This is often best done in a table(s). Graphs may also be
helpful. You decide which is the clearest way to express your data. Tables and graphs
need good titles and all numbers should have units and uncertainties if necessary. I will
now give you poor, fair, and excellent examples of a table. Let’s say that you did an
experiment in which you tested the effect of temperature on the heart rate of Daphnia.
Poor example:
Daphnia Data Table
Temperature
20.0
Trial
1
2
1
2
1
2
25.0
30.0
Fair example:
Temperature and Heart Rate in Daphnia
Temperature (oC)
20.0
25.0
30.0
Excellent example:
30.0
Trial
1
2
1
2
1
2
Heart Rate
116
124
147
144
182
188
The Effect of Temperature on Heart Rate in Daphnia
Temperature (oC)
( +/- 0.1 oC)
20.0
25.0
Heart Rate
116
124
147
144
182
188
Trial
1
2
1
2
1
2
Heart Rate (beats per minute)
( +/- 2 bpm)
116
124
147
144
182
188
Notice that the third table has a specific, descriptive title, units, and some mention
of the uncertainty in the measurements created by the thermometer used and the difficulty
in accurately counting heart beats in a tiny organism like Daphnia. If you feel there is no
uncertainty in the data, then state so and explain why you believe this. IB requires
demonstration of some technological competence so you are encouraged to use software
programs to generate spreadsheets, graphs, etc..
IB makes a distinction between raw data and processed data; you will see these
terms on the grading rubric. Raw data refers to the actual measurements you made in
the lab. These must always be reported in your Results. Processed data refers to any
calculations you made based on your raw data (such as a mean). You should show an
example of any calculations that you made. Consider uncertainties in your processed data
also. Raw data and processed data can go in the same data table.
Conclusion and Evaluation – Clearly state your conclusion here and relate it to your
hypothesis. Was your hypothesis supported or not? Why or why not? It is good to refer to
information in your textbook or elsewhere, if available, which relates to your conclusion.
Any sources that are referenced must be properly cited.You need to discuss what went
wrong in your lab and what could be improved and how. Evaluate the procedure. What
were its weaknesses and how significant were they? It is relevant to discuss the precision
and accuracy of measurements here. Modifications should address the quality and
reproducibility of the data. How can data be improved, error reduced, and variables better
controlled? Be realistic and specific. This section is frequently poorly done in student lab
reports - give things lots of thought.
I, __________________________, pledge that all my IB
lab writeups will be done independently by me and will
reflect my work only. Date:______________________