How to write a lab report Methods section
The format for the entire lab report is summarized in the handout of laboratory requirements. This handout will use a lab exercise on seed germination as an example of how to write a methods section. In each section of this worksheet there are questions that should be answered in reference to your experiment. You can then use the answers to these questions to your methods section for the assigned lab report.
General Rules for a methods section:
1. The methods section should be in past tense.
2. Do not list supplies used for the experiment as in a recipe.
3. Do not use narrative style writing, for example:
On Tuesday
we put five seeds into six Petri dishes.
Two
students took half of the seeds home and watered
them
each day.
4. A methods section should include a description of the
experimental treatments and sample sizes for each trial.
Experimental factors that were held constant and dependent
variables should also be described.
To effectively write a methods section you will need to know some aspects about the hypothesis for the experiment using the Erlenmeyer flasks. The hypothesis and prediction will indicate the treatments that are described in the methods.
The experimental hypothesis implies methodology for an experiment.
Included in the methods is a description of how the independent variable of
exposure to air was manipulated. However, the experimental methodology
should also include controlling factors. For the spontaneous generation
hypothesis all trials should include sterilized conditions. Having
sterilized conditions allows for conclusions about life from inorganic matter,
instead of life introduced into the flasks from the environment. If the
trial flasks were not sterilized, the experiment would not be testing life from
inorganic matter, but would test life arising from pre-existing cells.
Information needed before writing a methods section:
1. The supplies used during the experiment: growth substrate – nutrient agar broth
350 ml Erlenmeyer flasks
shape and straight glass tubing
sterilized cotton
an autoclave
From the list of supplies you should be able to identify the variables to include in a methods section.
A. independent variable: type of exposure to “air”
B. dependent variable: turbidity of agar broth (number of organisms)
Your methods section should also include conditions held constant during the experiment
For example: the nutrient agar broth (same broth for all treatments)
the sterilized equipment and type of growth substrate used was the same for all treatments.
Although you will use aspects of the hypothesis in the methods section, the statement of hypothesis is not included in the methods section (it is included in the introduction). There is an example of the format for a methods section on the following page.
Methods and
Materials
We used eight sterile petri dishes with filter paper as the germination
substrate for all wheat seeds. Six of the petri dishes were watered
with different concentrations of salinity. Two of the petri dishes were
watered with distilled water. Each petri dish contained five seeds and
was watered with 1 ml of solution twice a day. The wheat seeds were
allowed seven days for germination and seedling growth. Following
the seven-day treatments we calculated the percent germination and measured the
growth of any seedlings. The seedling growth was measured from the base
of the stem to the top of the stem, excluding leaf length. A comparison
of means test was used to identify differences between treatments.