Background
Write a
paragraph or two explaining why the
experiment you are writing about is
relevant to the study of biology.
How does it relate to what you are
learning in class? What process or
phenomenon will the experiment
support?
Research Question
This
is a single sentence which clearly
and specifically states the
objective of your investigation.
For a Design lab, the teacher cannot
give you detailed information and
guidance. Instead, you’ll be given
a general, open-ended problem such
as “Investigate the factors that
affect X”. You must do some
thinking to recognize the nature of
the problem that has been set, the
factors (variables) that will affect
the outcome, and how they affect it
(the hypothesis). So if a general
question has been posed, make it
more specific and relevant to your
individual experiment.
If
you're doing a controlled
experiment, your research question
must clearly identify the
manipulated and responding variables
for your experiment.
Selecting Variables
State variables explicitly, and
explain why each is relevant. All
reasonable variables that might
affect the outcome should be
identified. Indicate which
variable(s) is/are manipulated
variables (ones that you will
change) and which are the responding
variables (ones that will respond to
what you did). Indicate which
variables must be controlled and why
those variables must be controlled.
The
variables need to be explicitly
identified by the student as the
dependent (measured), independent
(manipulated) and controlled
variables (constants). Relevant
variables are those that can
reasonably be expected to affect the
outcome.
Hypothesis(es)
Although not required by the IB
Organization, for many labs you will
be asked to include a hypothesis. A
hypothesis is like a prediction. It
will often take the form of a
proposed relationship between two or
more variables that can be tested by
experiment: “If X is done, then Y
will occur.” (Examples: “The rate
of transpiration will increase as
wind speeds and temperatures rise”
or “Brand X toothpaste will be more
effective in preventing the growth
of the bacteria which causes plaque
on your teeth”).
You
must also provide an explanation for
your hypothesis. This should be a
brief discussion (paragraph form)
about the theory or ‘why’ behind
your hypothesis and prediction. For
example, why should raising the
temperature and increasing wind
speed increase the rate of
transpiration? Why is brand X
toothpaste more effective in
preventing the growth of the
bacteria which causes plaque on your
teeth?
Be
sure your hypothesis is related
directly to your research question
and that the manipulated and
responding variables for your
experiment are clear.
Apparatus and Materials
Consider making a list of
your experiment and materials
needed. Be as specific as
possible. (Example: “50 mL beaker
instead of ‘beaker’, type of
microscope with magnification
range).
A
diagram or photograph of how you set
up the experiment may be
appropriate, especially for more
complicated experiments. Be sure
your diagram includes a title and
any necessary labels.
You
might have to decide how much
of a substance or a solution to
use. If so, state your reasoning or
show the calculations.
Method/Procedure
State
or discuss the method
(procedure) that you are going to
use (or that you did use) in the
experiment. This should be in the
form of a list of step-by-step
directions. Provide enough detail
so that another person could repeat
your work by reading your report!
You
don’t have to go into detail about
standard, well-understood actions
such as measuring a temperature with
a thermometer, weighing out a
substance, etc.
If a standard technique is used, it
should be referenced. For example,
while planning an investigation to
study the effect of light wavelength
on the rate of photosynthesis in
Cabomba,
the student may have adapted a
method to measure the rate of
photosynthesis taken from a
textbook. A standard reference would
then be expected as a footnote, for
example, “Freeland, PW (1985)
Problems in Practical Advanced Level
Biology,
Hodder and Stoughton.” Or the
student may adapt a general protocol
provided by a teacher in a previous
investigation. The reference may
appear as: von Bargen, G (2007)
“Studying the rate of
photosynthesis” worksheet.
If you
do something in your procedure to
minimize an anticipated error,
mention this as well. (Example:
“Carefully cutting plant stem under
water to reduce affect of air on
transpiration rate.”)
In
your method, clearly state how
you will collect data. What
measuring device will you use, what
data will you record, and when? Or
what qualitative observations will
you look for (such as color change)
and what will you do when you see
this happen?
Multiple Trials
The
procedure must allow collection of
sufficient relevant data.
The definition of “sufficient
relevant data” depends on the
context. The planned investigation
should anticipate the collection of
sufficient data so that the aim or
research question can be suitably
addressed and an evaluation of the
reliability of the data can be made.
As a
rule, the lower limit is five
measurements, or a sample size of
five. Very small samples run from 5
to 20, small samples run from 20 to
30, and big samples run from 30
upwards. Obviously, this will vary
within the limits of the time
available for an investigation.
If a
reading is particularly different
from the others, it may be left out
of the processing and analysis.
However, you must always justify why
they have chosen to do this.
The data range and amount of data in
that range are also important. For
example, when trying to determine
the optimum pH of an enzyme, using a
range of pH values between 6 and 8
would be insufficient. Using a range
of values between 3 and 10 would be
better, but would also be
insufficient if only three different
pH values were tested in that range.
Safety
List
any safety precautions that must be
taken during the lab.
· “Wear safety goggles
throughout experiment.”
· “Be cautious in using
strong acids/bases. Rinse off
spills with water immediately.”
· “Avoid breathing
vapors of automobile exhaust.”
