How to Write a Lab Report

Wednesday, July 10, 2013
Why write lab reports?

Lab reports are a method for scientists to communicate their findings to others. Science is a group activity, so there must be an effective way for information to be shared.

A good lab report should be detailed enough that another person could duplicate your experiment exactly, at another place and time.

Parts to Include
  1. Title – A good title should be ten words or less and describe the content of the experiment. Information should be more important than creativity.
  2. Problem – What were you trying to find out? What question were you attempting to answer through this experiment? This part seems easy, but can often be one of the hardest sections to get just right.
  3. Materials – What did you use in this experiment. This can just be a list, and should include chemicals, supplies, equipment, etc. Anything someone else would need to know to perform the experiment exactly as you did.
  1. Methods – This is a step-by-step account of exactly what you did during the experiment. Include amounts of chemicals used, length of time you did things, etc. Again, this should allow another scientist to replicate the experiment. Where and when you performed the experiment can also be important, specifically in field studies.
  2. Results – In this section you will list what you found. Avoid any interpretation of the data, simply describe it. Data should be written out as well as presented in graphs, charts or figures. Information on how to produce quality graphs, etc. can be found below.
  3. Discussion – Now is when you can interpret your data. What do your results mean in terms of the original problem/question? Were there any possible sources of error in the experiment? How could the design or technique be improved? What further experiments might you want to do to answer more questions?

Ideally, scientific results should be separated from the scientists themselves. Therefore, it is common practice when writing lab reports to avoid using "I" or "we". For example, instead of saying “I weighed out 45 g of sodium chloride and added them to the solution”, you would write “45 g of sodium chloride were weighed and then added to the solution”. The "passive voice" is what you are going for.

The lab report should be clear and concise. Say what you need to say in as few words as you need. The discussion section is one slight exception; feel free to elaborate some on your interpretations.

Lab reports must be neat. Typed would be best, but if they are handwritten, anyone should be able to read and follow them easily. It is a good idea not to write the lab report as you are doing the experiment. This usually results in a messy and unorganized report. You WILL lose points for messy or grammatically incorrect lab reports.

Graphs and Figures
  1. All figures must have a title. Again, titles should be relatively short, and describe what the figure shows.
  2. Graphs must have both axes labeled. The X-axis (horizontal) should be the independent variable (the variable you do NOT change) and the Y-axis should be the dependent variable (the variable you change).
  3. Any lines on a graph or other representations of data should be labeled, if necessary.
  4. Line graphs should have best-fit lines. We will discuss what this means in more detail.
  5. Different sets of data should have different points – shapes, colors, etc. If you do have different sets of data, be sure to include a key.
  6. Graphs should be an appropriate size and scale.
  7. Graphs and all figures should also be neat and easy to read.