Lab Report

Lab reports must follow the format outlined below and described on the following pages.


How to write an Introduction section

 The Introduction section should include the following three sections.


Background information: This section presents information that familiarizes the reader with the subject of the experiment.

What to include: A well-written introduction should present information about all the

topics directly pertinent to the experiment. The Introduction section of the lab exercise

provides a brief summary of many of the relevant subjects.


How to write: Use well-structured paragraphs beginning with a topic sentence that

expresses ideas in your own words.


How to organize: Organize the information from the broadest topics that help to establish

relevance, to more specific topics pertaining directly to the experiment. For example the

paragraphs might be sequenced to explain:


• Why a nonscientist would be interested in the topic.

• How the topic relates to ecological concerns.


• The type of organisms, equipment, locations, etc. used in the study and why.

• Background information on topics the reader should know to understand the basis for the

experiment and its results.

 Near the end:

• The variable tested and why it may have an effect.

• What previous investigations have found.

How to use source information: Never directly copy or quote sentences from your sources.

Ideas should be conveyed in your own words, and the source of this information should be

cited and referenced (see description of Citations below).


Purpose: In a few sentences explain why the experiment was performed –what was the

scientific "problem" being studied and the objectives of the exercise. There are usually a

number of purposes to the lab exercise. Some purposes are educational in nature, such as to learn about experimental design.


Hypothesis: Remember, a hypothesis is one possible explanation of observations or

information. Whether your hypothesis is correct or not is irrelevant to your grade; frequently

the best lab reports are those that clearly explain why the hypothesis is incorrect.

How to write a Procedures section


 The objective of the Procedures section is to describe the experimental procedure in

sufficient detail for someone else to replicate the same experiment. The instructions provided in a lab manual should not be copied verbatim; they should be rewritten to provide the essential elements of the procedure, leaving out trivial details.


Essential elements of a Procedures section:

1. Sentences should be written in the third person passive voice.

Incorrect: “I measured the number of tree rings in cross-sections of 9 spruce trees.”

 This sentence uses the first person active voice.

Correct: “The number and width of tree rings were measured in cross-sections of 9

spruce trees.”

This sentence uses the third person passive voice. This style of writing is used to convey that the researcher was impartial and objective when performing the experiment and collecting the data.


2. All procedures should be presented clearly and accurately. The instructions of the lab

manual should be rearranged to form well-structured paragraphs.


3. Include all parts of the procedure that you performed, leaving out unnecessary, trivial


Incorrect: "I obtained 10 grams of NaCl from the front bench and dissolved it in 250 ml of water in a glass beaker. The data were recorded in a table"

 All of the underlined information is unnecessary;

Correct: “Ten g of NaCl were dissolved in 250 ml of water"

It is assumed that data are recorded. Note also that a sentence should not begin with an arabic number (i.e., "10").


4. Explain precisely how the data were collected.

 For example: “The width of the tree rings was measured in millimeters using calipers while

viewing the tree sections under a microscope.”


5. Explain how calculations were performed.

 For example: “The width of the tree rings was averaged for a 10 year span for all 9 trees

How to write a Results section


 The scientific data is presented in this section. This includes both qualitative observations

and quantitative measurements. You should include any observations that have bearing on the interpretation of the results (interpretation of the data are presented in the Discussion section).


Essential elements of a Results section:


1. Numbers should never stand alone ─they must be accompanied by appropriate units (e.g. ml, cm, cm/sec, etc.). Decimal numbers should always have at least one numeral before the decimal point (0.47g not .47g). Superscripts and subscripts should be used when needed; for example: 25°C, 80 cm2, and H2O.


2. There are two sub-sections of the Results:

 I. Tables and Figures

Presentation of data in properly structured graphs and tables.

 II. Description of Data

This is a paragraph-structured description of the data –in effect, narrate to the reader.


3. Characteristics of Tables and Figures 

A correctly prepared graph should:

1) be sequentially numbered (Figure 1, Figure 2, etc.)

2) have a descriptive title

3) have the independent variable on the x-axis

4) possess clearly labeled axes

5) have data points that are clearly marked.

A correctly prepared table should:

1) be sequentially numbered (Table 1, Table 2, etc.)

2) have a descriptive title

3) have rows and columns clearly labeled.

 4. The Description of Data (or Description of Results) section should:

• Be written in the third person passive voice.

• Describe the key features and trends that you perceive in the data presented in the figures

and tables.

• Not interpret the data. Explaining what the results mean or why the results occurred is

done in the Discussion section of the lab report.

How to write a Discussion section


1. The Discussion section includes three subsections:


 Explanation of results

 Future experiment


2. Conclusions: In a sentence or two, state whether the hypothesis is supported by the results or not. Identify any other conclusions pertaining to the hypothesis based upon the results of the experiment.


3. Explanation of Results: In this section you should explain and interpret your results and relate your results to information presented in the Background Information section and to other literature sources.


What are interpretations of results?

• Explanations of why or what caused the results to occur; and/or why did the results

supported or contradicted the hypothesis. As stated above, an incorrect hypothesis will

not tarnish your lab report, so you should explain the discrepancy based upon

biological principles.

• Suggestions and proposals of new biological principles and relationships.

• Comparing and contrasting with results and conclusions of previous studies.


Interpretations of results should draw upon and cite information from the literature sources,

and should not be vague unfounded ‘notions’ that happen to ‘pop’ into your head.


A poor Explanation of Results focuses on (for example) “experimenter errors” as a substitute for actually discussing the scientific meaning of the results in context of prior knowledge (from cited literature sources) about the topic.


4. Future experiment: This section shows how well you understand the experiment and its

results. In no more than two paragraphs, explain how another experiment might help to answer questions raised by the current experiment. Usually, the results of one experiment provide the basis for future related experiments, possibly in which other variables are studied. Be sure to state the purpose of the future experiment, but do not include a lengthy description of procedures.

How to write Citations and References 

 It is essential that you identify ALL sources of information and ideas included in your report. Do not be misled into believing that citations are only required for direct quotes. As stated above, sources should not be directly quoted in a lab report. You must, however, cite the sources of information and ideas that you express in your own words.



 'Citations' within the text of the report point to the original source of information, and are

most commonly used in the Background Information and Explanation of Results sections.

Footnotes or subscripts are not used to cite sources in scientific writing. Although the format used for citations varies among disciplines, the following format could be used:

 (Author(s), year of publication, page #)


If the source has a single author, then the citation is written as:

 For example: (Smith, 1992, 97)


If the source has two authors, then the citation is written as:

 For example: (Smith and Jones, 1997, 184)


If the source has three or more authors, the abbreviation

‘et al.’ is used after the first author’s name:

 For example: (Smith et al., 1997, 184)


Proper Use of Citations

1) Citations must be accurate to the source of information – to the indicated article and page.

2) Citations should refer to a single page. This is not acceptable: “(Jones, 1997, 23 – 25)”. If the referenced information begins on one page and continues on the next, just cite the first page. If distinct information is being cited from several pages, a different citation must be used for each.

3) Do not cite from abstracts, cite only from the full text of an article.

4) Do not cite only at the end of paragraphs; citations should be included throughout a paragraph to prevent ambiguity as to the source of information.

5) Every citation must also be listed in the Literature Cited; every source in the Literature Cited but actually be cited in the text.


Citations point to 'references' listed in the "Literature Citations" or “References” section of the lab report, where the sources of the information are listed alphabetically.

Acceptable sources include scientific articles published in books, science magazines and scientific journals. The course textbook and lab manual could be used (if allowed by your instructor). Do not use mass media magazines, websites and newspapers.  

MLA, APA, or Chicago style are acceptable for most reports.  (feel free to use

Need Help?  Here is a pretty succinct site summarizing how to do a basic lab report