Writing in the Sciences: The Lab Report

  • Clarity, Conciseness and Cohesion are the 3Cs of scientific writing.
  • Specific content within a rigid structure often makes scientific writing difficult. In creative academic writing, a structural component is also present (introduction, thesis, body paragraphs, conclusion), but it is much less apparent because each part very rarely, if ever, gets labeled.
  • Scientific writing uses specific, often very technical language, voice, tense and style. Most
  • often passive voice is used in biological, chemical, and physical sciences; use of “I” or “we” is avoided. Behavioral sciences prefer active voice.

                 Active Voice: I placed the DNA in the fridge overnight.

Passive Voice: DNA was incubated at -10 degrees C for 12 hours.

  • In scientific writing, a certain structure is accepted:


Introduction, Materials and Methods (Procedure), Results, Discussion, Conclusion.

  • Past tense is generally used for the Methods and Results sections (for any referral to the lab or experiment); present tense is used for the Discussion section.
    • Unnecessary words are eliminated (extremely, commonly, actually, basically, perhaps, seem, appear, quite, always, very). The verb should be placed near the subject, and known information should precede unknown information. Follow the logic. Example:

 Wordy: Curiously, I noticed a fair bit of variation in the DNA yields which seemed surprising.

                  Concise: Substantial variation in DNA yields was observed.

  • Transitions are used to maintain good connection between the previous information.
  • Correct word choice is important (to describe, to illustrate, to show, to note, to state, to stress, to point out, to analyze, to conduct, to maintain, to speculate, to observe, to comment).
  • Direct quotations are not accepted in lab reports.


Organization of the Lab Report


  • Provides a short background on the experiment and answers the question why this experiment/ lab is important.
  • Addresses expectations and predictions for the experiment and states a hypothesis, if relevant.

Incorrect: The length of refrigeration period will affect DNA yields. (Not specific enough)

Correct:  Longer periods of refrigeration will increase DNA yields.

  • Describes what approach needs to be used to answer the research question or hypothesis and connects the experiment to the bigger picture. Understanding the big picture/experimental question is important. Professors/instructors love to ask this big picture question. How does this experiment relate to a bigger idea? (Hint: if it’s not clear, ask questions. Approach students as experts in their fields and let them explain why.)

Materials and Methods (or Procedure)

  • Describes with clarity and logic a set of procedures (protocol/steps) and equipment used for the experiment so someone from the field could easily repeat it. (Hint: imagine just for fun that you are going to do the experiment. Are all the steps in logical order?)
  • Cites the lab manual or other sources, if relevant. Students are not the ones who created the experiment, so it may be important to refer to the appropriate source.


  • Contains data obtained during the experiment, such as text, figures, tables, and calculations.
  • Labels figures and tables clearly, including units of measurement.
  • Describes and references tables and figures in the report (e.g. “DNA yield in frog embryos decreased with age of embryos, as shown in Table 1.”)
  • Presents results in a clear and concise manner.


The professors/TAs look for these indicators of logic, clarity, and critical thinking in lab  reports:

  • Interpretation of the results with “big picture” in mind,
  • Convincing attempt at interpretation of data,
  • Use of citations if comparing existing literature evidence with lab results,
  • Comparison of actual and expected results. Answers to questions “What was expected? Why?”
  • Analysis and explanation of experimental errors,
  • Explanation of unexpected data,
  • Suggestion for improvements or any further investigation based on the current experiment,
  • Explanation of reason to accept or reject hypothesis stated in the Introduction.


  • Consists of a couple of sentences to summarize the results of the lab or experiment and to

relate them to the purpose.

  • If required, includes a reference list and appendices to place data, such as tables, graphs, and calculations.


Created by Elena Kalinina-Turner and Gourav Nandi for the MSU Writing Center, March 2013