The purpose of lab report is to:
1) record changes in variables
2) communicate observations
3) interpret observations.
Parts of the Laboratory Report
Experiment title on a title page
Although self explanatory, the title helps you, as the student, define your understanding of the laboratory
experiment. The title page also indicates the names of the lab partners, the date the report was handed in
and the course number.
A brief description (in your own words) of what scientific principle is to be tested or verified. The
purpose of a lab experiment is to test a hypothesis. In most of our labs, you will be given a question or a
hypothesis to design your own procedures to test.
Materials and Method (Procedure)
First, list all the materials that will be needed to carry out the experiment. Then, briefly outline of the
experimental procedure. A detailed report of all the steps taken is not necessary. By including a procedure
outline in the report your attention is focused on what happened during the experiment. If the procedure
is provided to you, you must note any modification made to that procedure. Try to avoid writing your
procedures using the past tense or passive form.
Data Collection
Presentation of data in tables allows easy following of the coming data manipulations. Tables should be
clearly labelled as to their content and numbered for ease of referral in the discussion section.
Therefore, some estimation of the experimental uncertainty is necessary to help explain the results and
to verify if the scientific principle tested holds. Part of the data may involve making observations (color
changes, temperature changes, melting point, boiling point, the physical appearance of a chemical
substance, etc.)
Calculations, result table and graphs are ways to express results.
Experimental error analysis
Some of your lab questions might have answers that have been repeatedly obtained and generally
accepted as correct. This number would be called the theoretical value. When you perform an
experiment and get a number, that number would be called the experimental value. When a
theoretical value is known, you can determine just how good your experiment is and how well your
procedures were done by using the following equation to calculate the experimental error.
% error: theoretical value – experimental value
theoretical value
This section requires looking at the experiment’s purpose, the data, the graph and the calculation sections
of the lab report and bringing them all together. Sometimes it involves the comparison of the student's
experimentally derived answer to a known literature value. Other times, it requires the student to identify
an unknown from a list of unknowns based on the information gathered during the experiment. Sometimes,
you will be asked a series of questions that should guide your thinking. In the discussion section.
Summarize the essential lab data. Show how the essential data answers the hypothesis/purpose of the
experiment. Identify the one area of the lab most likely responsible for measurable experimental error.