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.