Theories,
Models,
and
Hypotheses
Materials and
methods
Results:
presenting
data
Results:
interpreting data
Conclusions
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Materials and Methods
The materials and methods section is similar to an instruction manual.
It should describe the apparatus and the procedure that you used in your
experiment. Almost all research reports will include a materials and methods
section. As always, it is best to ask other experienced writers in your
field for advice, or to critically consider other models of writing in
your workplace or discipline as possible models.
This section should be clearly and specifically written; another researcher
should be able to exactly duplicate the research you performed by following
the procedures outlined in this section. However, since some procedures,
materials, and methods are standard to your field, you do not necessarily
need to describe ones which a researcher in your field would already understand
or which are common knowledge for your field. You should decide which
actions and features of the research are standard for your field and will
be understood easily by readers and which will need in-depth and careful
explanation. If your report serves to introduce any new action or feature,
be sure to thoroughly outline the action or feature in the materials and
methods section.
All materials and methods sections should address the following questions:
- How was the experiment designed?
- On what subjects or materials was the experiment performed?
- How were the subjects/materials prepared?
- What machinery and equipment was used in the experiment?
- What sequence of events did you follow as you handled the subjects/materials
or as you recorded data?
Some other issues that might be relevant to your research and that should
be addressed in the materials and methods section are listed below:
- Describe in detail any special or nonstandard equipment used. Consider
providing an illustration of the equipment.
- Describe the method you used to record data .
- Include the species, genus, strain, and breeding origins of any animals
used.
- Describe the amount and purity of any chemicals used.
- Describe in detail any part of the experimental procedure that is
original.
- List any dangers or potential problems that might result from the
experimental procedure. It is a good idea to include these in a separate
paragraph of the Materials and Methods section labeled “Caution.”
The example “Materials and Methods” section below was taken
from a student lab report. The subject of the report was “Cardiac
Muscle and Cycle.”
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Materials and Methods
To perform this experiment, the following equipment is needed:
the Physiograph VI, myographs A and B, two tension adjusters, two
transducer stands, calibration weights, the Grass stimulator and
isolation unit, stimulator cable, two pin electrodes, two sleeve
electrodes, the ECG pre-amp, a thermometer, saline solution and
dish, and the suture board. Begin by collecting the pithed turtle
and removing the plastron disk to expose the heart. Throughout the
experiment, keep the heart moist with addition of saline to body
well. Mount the B myograph above the hole and connect with suture
to the frenulum, near the ventricular apex. Remove the pericardium
(except for a small amount near suture) so that the ventricular
pull is wholly communicated to the myograph. Adjust the tension
in the suture until all slack is removed. Obtain a suitable recording
of contraction and relaxation; measure heart rate and systolic and
diastolic periods. Note heart temperature. Record ventricle activity
while increasing myograph tension – verify Starling’s
Law. Attach a hook electrode to the ventricle apex. Connect the
A myograph to the left atrium with the other hook electrode. Connect
electrodes through ECG pre-amp to measure EGC. Obtain a three-channel
reading of EGC and atrial and ventricular contractions. Insert two
pin electrodes into the apex and middle of the ventricle. Connect
to Grass stimulator through isolation unit and record the effects
of stimulation. Find the refractory period. Connect the stimulator
to the right vagus nerve with a sleeve electrode. Record slowing
to arrest caused by stimulation. Connect to left vagus nerve and
record the inotropic effect on the atrium caused by stimulation.
Also record the shortening of the refractory period with stimulation.
Finally remove the heart to saline dish and record an EGC of the
isolated heartbeat.
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