Reproducibility is one of the most important concepts in our
modern scientific method. When one team tests a hypothesis and
publishes their results, it only becomes accepted by the scientific
community when other teams can reproduce the experiment and get the
same results. Therefore, it is crucially important to write a
clear and detailed procedure so that other people can replicate your
experiment in the exact same manner as you performed it.
When writing a procedure, you must be very thorough.
Remember, your goal is to write directions down so that someone else
can perform the experiment exactly the same way that you did.
Tips for writing a procedure:
Include
a Materials List
Materials list needs to be
specific including the quantity of items used and what specific
size of equipment
Most glassware is specifically
named not by just the type of glassware, but also the size
Examples:
Detailed
Unclear
150mL Beaker 10 mL graduated
cylinder Red food coloring
Beaker graduated cylinder food coloring
Organize the Procedure in a Step by
Step Format
Numbering each step is often the most clear, but not mandatory.
Be Detailed
Measurements
- list the specific instruments used
Be sure to state what measurements you made, when you made
them, and what instruments you used
Ex - "1. Use a 150mL beaker to measure out 100 mL of cool
tap water."
Ex - "2. Use an electronic balance to measure the mass of
the precipiate and record the mass in your data table."
Language Tips:
In chemistry, we measure MASS and not WEIGHT
If you unit is grams, then you did not "weigh" it -- you
measured its mass.
You make measurements, you do not "find" them.
Do not say "Find the mass of the sample", say "Use an
electronic balance to measure and record the mass of your sample"
Do not inlude the data from your measurements in your
procedure. The results of your measurement go in the data tables
in the results and analysis section of your lab.
Ex - "The mass of precipiate was measured and determined to
be 34.76 grams" -- The 34.76 g is your data and it should not be
included in your procedure.
Give Time
Parameters
Examples:
The solution was stirred for 2 minutes
The beaker with solution was left out uncovered on the
window ledge overnight
The water was heated over the bunsen burner until little
bubbles covered the bottom of the beaker
Note Temperature
Examples:
The sample was placed in a drying oven set at 45 °C for
2 hours.
25 mL of cold tap water was added to the solution
Use Diagrams
Pictures can make clear what you are trying to say with words
Be sure to label diagrams (ex - Figure 1) so that you can
reference them in your text.
Do not include calculations
in the procedure section.
Just like your measurement data, this all goes in the results
and analysis section.
Example:
Use a ruler to measure the length, width and height of the
cardboard box and record these values in your data table. <-- This does belong in the
procedure section.
Calculate the volume of the box by multiplying the length x
width x height. <-- This is a
calcuation and does not belong in the procedure section.