Appendix A: Lab Report Writing Guide

Appendix A

University of Baltimore Biology Laboratory Report Writing Guide


Lab reports are structured very specifically and include the following sections, which with the exception of the Title page, are in paragraph form. A paragraph is four to six sentences.

I. Title page

II. Introduction (~3 – 5 paragraphs)

III. Methods (~1 – 2 paragraphs)

IV. Results with tables and/or figures (1 paragraph + tables/figures)

V. Discussion (~3 – 6 paragraphs)

VI. Conclusion (1 paragraph)

VII. Works Cited

Report construction: 12-point Times New Roman font, 1-inch margins on all sides, 1.5 or double-spaced. All tables can be constructed and directly copied out of Word or Excel, as well as any charts.


I. Title

The title is used to inform the reader about the research question you are investigating. The title should be on a cover page that also includes your name, lab section number, instructor’s name, and the date.

II. Introduction

Introductions are generally three to five paragraphs of all the background information that a reader needs to understand your experiment and any results or conclusions resulting from the experiment.

For example, if I were writing a report on an experiment that tested how different fertilizers affected tomato plant growth, my introduction would need to include information about the biology of tomato plants (What kind of plants are they? What habitats/soils do they prefer to grow in?), how fertilizers affect plant growth (what kinds of nutrients do plants need to survive?), and some explanation of how fertilizers might affect the tomato plants in this experiment based on the information I presented earlier in the introduction.

Introductions should include:

A. Information that a reader needs to know and understand, to understand the science behind the experiment.

    1. Identify the Broad Biology Concepts that related to my investigate and talk about them
    2. Why are they important? Why should we care?
    3. Provide background information that a reader would need to understand your results and why your results matter. Use outside sources.
    4. State the objective/purpose of the research
    5. Provide a hypothesis (or two or three) and explain your reasoning for thinking that using science.

B. This information you provide should be cited from outside sources, which can include your lab manual, lecture slides, textbook, and scholarly sources. These should be cited in the text, and the full citation of the source should be included in the Works Cited.

C. Hypothesis/es

  1. Hypotheses are usually presented in the last paragraph of the Introduction.
  2. Your hypothesis is a prediction that you make based on information. A hypothesis must (MUST!) have a “because why” statement.
  3.  Ex: “I think that Black Panther will be a great movie” is not a good hypothesis – where is your evidence? A good hypothesis would be “I think Black Panther will be a great movie because it has an all-star cast and a 97% rating on Rotten Tomatoes”. This hypothesis provides evidence, or a “because why” statement.
  4. It is ok to have more than one hypothesis (some experiments have multiple questions), just remember that each hypothesis must have a “because why” statement.
  5. Include a sentence about how you tested your hypothesis (aka what was the purpose of your experiment?)


III. Methods

A. Discuss the methodology used, sequentially and in detail. DO NOT write a numbered step-by-step procedure. DO NOT write a materials list. NO LISTS.

  1. Answer: Where? How? Who? What data was collected?

B. The materials/equipment/chemicals you used should naturally be discussed when your write the methods (Ex: “We used a ruler to measure the height of the plant in cm”, “We tested for the presence of starch using iodine solution”)

C. You can use first person (“I” or “we”)

D. This is not meant to be a play-by-play! If you repeated the same procedure and only changed on part of it (For example, in our hypothetical tomato experiment, each tomato plant was potted the same but was watered with water mixed with a different fertilizer), you do not have to rewrite the procedure four times, you only need to write the procedure once and explain which aspect of the procedure changed during the experiment.

E. You MUST include how your analyzed the data – what kind of statistical test did you perform?


IV. Results

A. Include a short (~1 paragraph) narrative giving the highlights of your results. For example, the greatest/least results, the range of your results, whether your results were statistically significant, etc. Basically a brief summary of what your results were (pull these numbers from your table/figures).

B. Do not explain your results (that’s what Discussion is for!). The Results section is “This is what my data are/this is what my results came out to be” and the Discussion section is “these were my results and this is why”

C. Tables and Figures – these should compile and summarize information.

    1. Both should include “stand alone captions”. If the page containing just your table/figure was left on a kitchen counter and somebody else found it, they should be able to know what they are looking at in your table/figure based on your caption alone. Captions need to be somewhat detailed, so they can be a few sentences.
    2. Tables have captions ABOVE the table
    3. Figures have captions BELOW the figure
    4. Figures should include a title, key (if appropriate), and proper x-and-y-axis labels.


V. Discussion

A. Briefly summarize your experiment/investigation and discuss what these results mean and whether they do or do not support your hypotheses. If your results were surprising, talk about why they were surprising.

B. Address your hypothesis – what was your hypothesis and can it be supported by your data? (Cite your data numbers!). And then explain WHY it can/cannot be supported by your data using outside sources. What existing science can you use as evidence to support your conclusions?

C. What were potential sources of error in your investigation? “Human error” is not an acceptable source of error, so be specific.

D. How could you expand on your investigation? How could you change the investigation/experiment to answer different questions in the future, or to explore some different aspect of the science?

E. How does this investigation/experiment relate to the Real World or the Bigger Picture? Give an example or two.


VI. Conclusion

A. One paragraph, maximum

B. Sum up your lab report

    1. Why was this topic/your investigation important to begin with?
    2. What were your findings? (briefly)
    3. How is that important to the Real World/Big Picture moving forward?

C. Summarize what you said in Discussion about how this experiment relates to things beyond lab (a broader context).



VII. Works Cited

A. References should be cited alphabetically by the last name of the author (use the first author if there are multiple authors).

B. In text citations should be cited as (Author last name, year) following the information from that source

    1. Two authors generally get both their names in in-text citations
    2. Generally, for sources with more than two authors, cite them as (First listed author last name et al. year), and then list out all the authors in your works cited section.

C. Which citation style you use is up to you (MLA or APA style are pretty standard), but be sure to be consistent throughout your report.

D. For help with citations, check out Purdue’s OWL site:


VIII. Very helpful science grammar tips

A. Writing quality matters! Read your report out loud to yourself. If it sounds funky when you said it, try using a different word (Do your subjects/verbs match? Are you missing words? Did autocorrect change the word to something not correct?)

    1. Ex: the word “data” is plural (the data are). “Datum” is the singular version (datum is).
    2. Spelling à regularly proofread and perform spellcheck!

B. It is perfectly acceptable to write in first person (i.e. “I performed an experiment” or “We performed an experiment”). Writing in third person (i.e. “This was done”) is a tedious, roundabout way to write about science. Very few science disciplines still write in third person, but chemistry and entomology are two of them.

C. Science writing is a more formal way of writing. So you should NOT:

    1. NO contractions (Ex: can’t, don’t, didn’t, etc.)
    2. Start sentences with “And”
    3. Use rhetorical questions
    4. Use information language in lab reports. Don’t get fancy, just get to the facts.
      • Good: We tested the effect of temperature on reaction rate
      • Poor: Then we decided to look at enzyme reaction rate.

D. When to use word numbers vs. alphanumeric numbers

    1. For numbers 1 – 10 write out the word (Ex: one, nine, ten)
    2. For numbers higher than 10: write the alphanumeric number (Ex: 208, 429, 10,000)
    3. Exceptions:
      • Table/figure captions always use numbers
      • Numbers beginning a sentence must be written out in words
      • When reporting results in a Results section, use alphanumeric numbers.
      • When talking about measurements  (Ex: 5 mL, 3 cm), use alphanumeric numbers

E. Number grammar

  1. Decimals cannot be naked!
    1. A decent, clothed decimal: 0.94; 0.1034
    2. Naked decimal: .94; .1034
  2. Scientific symbols
    1. Put a space between numbers and symbols.
    2. Ex: “50 cm” vs. “50cm”
    3. Ex: “9 > 5” vs. “9>5”

F. Effects vs. Affect

  1. Affect is the verb, effect is the noun
  2. Affect = “to have an effect on” (verb)
  3. Effect = “the result, consequence, or impression” (noun). Rarely used as a verb, where effect = “to bring about”


Share This Book