IB Biology Internal Assessment Lab Format
IB Biology—Lincoln High School, Lincoln Nebraska
Title: Include independent variable, dependent variable, scientific name Genus species and (common name) of
any organism you use.
The following titles and subtitles should be used for your lab report and given in this order within your lab report.
Design
Introduction—A few paragraphs that provide the reader with some background information regarding your topic.
Be sure to introduce the biological principles and explain the concept(s) that is being investigated. Show an
independent understanding of what you plan to do in lab. Provide the scientific name of any organism used
(Genus species)
Be sure that if you do your experiment for a certain about of time that the time frame you chose is referenced
here.
Use footnotes to site sources
Aim—Provided by the instructor
Question – must be focused and not ambiguous in any way. The independent and dependant variables must be
clearly identified. Often, but not always, the RQ is written as,
“What is the effect of __IV__ on __DV__?”
Hypothesis – This must be an ‘if-then statement. State first & then give a logical rationale – your conclusion
should address the hypothesis you are giving here. The hypothesis will often take the form of a proposed
relationship between two or more variables that can be tested by experiment.
Hypothesis statements are often written as:
If __describe IV_manipulation__, then __ expected result on the DV__ because __explain why_. This should be
a brief discussion (paragraph form) about the theory or ‘why’ behind your hypothesis and prediction. You should
site credible references that support your explanation
Variables – chart
Independent Variable-- Explain what you plan to change, the INDEPENDENT VARIABLE. Indicate the range
of the independent variable and list the levels of the IV that you included. Typically you should have a
minimum of 5 levels of the IV.
Dependent Variable-- You need to explain what will be measured, the DEPENDANT VARIABLE. State what
will be measured (both qualitative and quantitative data) and explain how it will be measured.
Controlled Variables-- At least three INDEPENDENT VARIABLES that will be CONTROLLED in your
method are required, but more may be necessary. The controlled variables you list must be relevant to your
investigation.
You need to control for all variables that may reasonably affect the outcome of the investigation. Materials
used and measurement techniques are NOT controlled variables
You must explain why and how variables were controlled.
Often students create a table to organize this information:
CONTROLLED VARIABLES
1.
2.
3.
WHY in must be controlled
HOW it was controlled
Make a list of the EQUIPMENT needed in the investigation. Be as specific as possible (example: ’50 mL beaker’
instead of ‘beaker’); include the volumes of tubes and cylinders, the concentrations of solutions, the model and
manufacturer of any complex apparatus. If you have to decide how much of a substance or a solution to use,
state your reasoning or show the calculations.
Protocol Diagram or Photograph of Lab Setup – draw & label a diagram which best shows the major
protocol(s) you used. Often this will focus on the technique that was used to measure the dependent variable
and/or the technique that was used to ‘setup’ different increments of the independent variable. Make sure to
show how control group(s) differ from experimental group(s). This is also where I want you to emphasize the
inclusion of a period of time for ‘equilibration’ of equipment, fluids, organisms, etc. The inclusion of time periods
for equilibration should also be included in your written procedure. Aannotate this to show how variables were
instituted, especially the controlled variables. Do not just label equipment.
Procedure – write in LIST form, passive voice, and past tense. Describe the METHOD that you plan to use in
the experiment. This should be a list of step-by-step directions. Provide enough detail so that another person
could repeat your work by reading your report.
You may need to try the experiment to know exact volumes.
o
Your procedure should include a few MEASURES FOR PERFECTION (i.e. cleaning test tubes prior to use,
cleaning the microscope lenses, using the same ruler…). These make sure experimental measurements are
consistent.
o
Your procedure must CLEARLY STATE HOW YOU PLAN TO COLLECT DATA. What measuring device
will you use, what data will you record? What qualitative observations will you look for?
o
Explain how you set up the investigation so you had MULTIPLE TRIALS of data collection. The procedure
must allow collection of “sufficient relevant data”. The definition of “sufficient relevant data” depends on the
context.
o
The planned investigation should anticipate the collection of enough data so that the problem question can be
suitably addressed and an evaluation of the reliability of the data can be made.
o
As a rule, the lower limit is a sample size of five. Very small experiments could collect 15 pieces of data, but
some professional trials collect 100 repeats of each piece of data. Obviously, you must plan something within
the limits of the time available for an investigation.
o
If you are SAMPLING only a portion of a population, you must explain how and why you ensured that the
sample was randomly selected.
o
Your procedure must be safe and ethical. Organisms, including humans, can not be subject to harm in your
investigation. Refer to the Experiment Ethics Document, and list any SAFETY PRECAUTIONS that were
taken during the lab.
Data Collection and Processing
Raw Data Table – make sure this is raw data only. Data table design & clarity is important. A title should be
given (Raw Data Table is not a data table title, it is a lab report section title) Make sure that all columns, etc. are
properly headed & units are given. Forgetting one unit or misidentifying one unit is enough to drop your score in
this section. Do not “split” a data table (putting part of a table on one page and finishing it on another). If you
absolutely have to split a table (due to quantity of data), make sure that you re-do the title and all column
headings. Uncertainties are mandatory and can be given within column headings for equipment precision and as
footnotes beneath data tables for other types of uncertainties.
Data Processing
Overview – this is a short paragraph section that gives an overview of how and WHY you decided to
process and present the data in the form that shows up later in this section.
WHY did you take the average?
WHY did you find the standard deviation?
Sample Calculation – neatly lay out and explain one example only of any type of manipulation that was
done to the raw data to help make it more useful for interpretation. If calculations were completed using
Excel you must state that this is the program used to complete all calculations.
Presentation – this is typically one or more data tables (of your now processed data) and one or more graphs of
this processed data. Once again, the design & clarity of data table(s) is important and the quality of graphs is also
very important. Give careful consideration to the choice of graph style(s) that you choose to do. Think about
doing a scatter plot or perhaps a line graph showing error bars or any number of other creative graphing styles
rather than just a simple line graph. Remember that demonstrating errors and uncertainties in your data is also
mandatory for the processed data. Make sure that you follow good standard rules for doing graphs (valid title,
axis’ labeled including units, etc.)
Be sure that you have a title for EVERY GRAPH AND TABLE
Be sure that your column heading could ‘stand alone’ in meaning. Don’ label your column headings ‘trial 1, trial 2
etc’.
Annotate all graphs/tables/images
Note: Weak experimental design can sometimes limit you to pie graphs and/or bar graphs; avoid this by
good experimental design in which you have a quantitative independent variable (with well chosen
incremental values) as well as a quantitative dependent variable.
Conclusion & Evaluation
Conclusion - this is a paragraph section in which you get a chance to discuss the results of your experiment.
Start by addressing whether your data seems to support or refute your hypothesis. This should be discussed and
not just stated. Specifically refer to your graphs to give support to this discussion. Avoid the use of the word
“proof”or “proves” within your conclusion, as your data will not prove anything.
MUST DISCUSS IF DATA IS SIGNIFICANTLY DIFFERENT
**EXPLAIN THE BIOLOGY/CHEMISTRY/PHYSIC BEHIND THE CONCLUSION STATEMENT.
Limitations of Experimental Design – this paragraph section discusses how well your experimental design
helped answer your experimental question. What worked well (and why) and what did not work well (and why).
This is also a section in which outlier points could be discussed (if there were any outlier points) as well as
possible reasons for those outlier points. If you did any statistical tests, what did the results of that test show? If
you have error bars on your graph(s) what do those show?
Random vs systematic errors
Sample Size
Suggestions for Improvement - In reference to the limitations given in the previous subsection, what realistic
and useful improvements could be made if you were to do this investigation again? Try to avoid superficial
suggests such as ‘reduce human error’. Certainly you can mention this but remember, the world is your oyster to
a certain extent. Do some research and look for ideas/better equipment to improve your experiment. Obviously
you cannot go out and purchase an electron microscope nor can you use a PCR (Polymerase Chain Rection)
machine. Even if you did not purchase the machine, just using it once costs a hospital $5,000 (This is the cost
charged in an episode of ‘House’. I am not entirely sure that this is the real cost, but you get the point).
Students: Refer to the Internal Assessment Grading Matrix given to you earlier for a complete picture of how you are
evaluated on each of the three criteria:
 Design
 Data Collection and Processing
 Conclusion and Evaluation