Writing Manual

Grammar and Sentence Structure

To write effectively, you have to consider not only the substance and style of your paper, but also punctuation and grammar. The following list represents some of the most common errors we have seen in student papers over the years. For others, consult one of the comprehensive style manuals listed in the References on Writing section of this manual. The UW-Madison Writing Center also has a very useful grammar and punctuation website.

Agreement in Number

  • Subject and Predicate: A predicate is a verb or verb phrase of a sentence. Predicates should agree in number with their subjects. Units of measure are often used in the collective sense and the verb should be singular.

The datum is… (singular)

The data are…(plural)

Five milliliters of water was added to the mixture.

  • Pronouns: Traditionally, the rules of formal academic writing have held that pronouns should agree in number with the noun to which they refer. Following this convention, a sentence might look like this:

Everyone (singular) must hand in his (not their) lab report on time.

This convention is shifting as more people are using the word “they” as a gender-inclusive singular pronoun.[1] In the Biocore program, our goal is to help you understand the traditions you participate in as a writer, and we will expect you to demonstrate that you are engaging with the conventions active in the field in an intentional way. You may use a “singular they” in your work, but if you do so, please include a footnote that indicates that you are using ‘they’ as a singular pronoun. Append this footnote to the first instance of the “singular they” in your writing.


Ask yourself whether you did something (past tense), are doing something (present tense), or will do something (future tense).

  • Describe your completed observations and procedures (e.g., the Methods and Results sections) and published research in the past tense.

We obtained samples from three different sites.

Leaf area increased in plants grown under higher light intensities.

McGee (2010) reported that taller Biocore students wore larger shoes.

  • Use the past perfect tense when events are repeated or continued from the past to the present.

Gall formation in goldenrods has been studied in many geographic locations.

  • Describe generalizations, conclusions, and references to conditions that continue to be true in the present tense.

Streptomycin inhibits the growth of M. tuberculosis.

Our data suggest that algae, like all autotrophs, require and may be limited by light, water, gases, and mineral nutrients.


  • Comma: Include commas after each word, phrase, or clause in a series, and before the conjunction separating the last two.

Grasses, legumes, and composites grow in Wisconsin prairies.

Commas should follow that is, for example, moreover, i.e., and e.g.

For example, most Iron Age graves consist of burial mounds sheltering only one individual.

The Nature Conservancy has completed a preliminary series-level (i.e., dominant plant species) classification for the western United States.

  • Semicolon and Colon: Use a semicolon between parts of a compound sentence (two or more independent clauses) not connected by a conjunction, such as and, but, or.

Light consists of energy packets called photons; the shorter the wavelength of light, the more energy in its photons.

Put a semicolon before, and a comma after, each conjunctive adverb, such as moreover, therefore, nevertheless, consequently, or furthermore, when connecting two parts of a complex sentence.  Use commas when these words are used at the beginning of a sentence or when they are part of a simple sentence.  (In general, avoid these “filler” words as much as possible!)

The deionized water was not available; however, we still completed the experiment.

Therefore, the results were significant.

Researchers working in other areas, however, failed to document the importance of competition, predation, and disturbance.

Use semicolons when commas occur within one or more of the elements of a series.

Familiar examples of species that are extremely vulnerable to human activity are the northern spotted owl, threatened by logging of old-growth forests in the Pacific Northwest; the red-cocked woodpecker, endangered by logging of longleaf pine forests in the Southeastern Coastal plain; and the desert tortoise, often shot or run over by motorized recreationists.

Three cities I will visit are Madison, Wisconsin; Northfield, Minnesota; and Chicago, Illinois.

Use colons to introduce a part of a sentence that expands or clarifies the meaning of what precedes it.

The instructor expects the following students to complete their lab reports early: Anna, Dmitry, Jaafar, and Darla.

  • Quotation Marks: Place a comma or period inside the quotation marks whether or not it is part of the quotation; place punctuation other than a comma or period outside the quotation marks unless the punctuation is part of the quotation.

We don’t label data as “good” or “bad”; however, we can label them “surprising.”

  • Parentheses: Use parentheses (these things) sparingly. If the words you are enclosing within a parenthesis are not important enough to be included in the sentence, they may be superfluous. Use parentheses for comments or explanations that are independent of the sentence.

Solar energy is the basis of virtually all food chains (rare exceptions include chemically based communities in deep-sea vents) and is converted to chemical energy by photosynthetic plants.

Use parentheses to enclose abbreviations and acronyms after they are spelled out.

The Global Biodiversity Strategy (GBS) was developed by the World Resources Institute (WRI) and the United Nations Environmental Program (UNEP).

  • Underlining and Italics: Italicizing and underlining are used for the same purposes. Italics are preferred and are easy to do with a computer. Italicize the titles of books and periodicals.

Curt found the article in the journal Ecology.

Italicize a genus or species name (and capitalize the genus name).

Poison ivy (Toxicodendron radicans) produces a secondary compound which causes an irritating rash on the skin of many people.

Italicize foreign words and abbreviations based on them (e.g., the abbreviation e.g.)

  • Dangling Participles: Participles are verb forms having qualities of both verb and adjective. In the present tense, participles frequently end in -ing (asking); in the past tense, participles commonly end in -en or -ed (asked, spoken).Dangling participles are participles (often acting as adjectives) that modify the “wrong” noun.

POOR: A bubble was observed in the jar using a magnifying glass. (The jar is not really using a magnifying glass!)

BETTER: We used a magnifying glass to observe a bubble in the jar.

  • Abbreviations, Acronyms, Numbers: Write out a term the first time before abbreviating it.

The enzyme isocitrate dehydrogenase (IDH) catalyzes the oxidation of…

Express numbers as figures; do not write out the number name. A sentence, however, should never begin with a figure:

Twenty-two gazelles ran past me. Next I counted 10 antelope.

  1. For more information, see Indiana University's Academic Style Guides on the Singular Pronoun 'They.'


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Process of Science Companion Vol. 1 by University of Wisconsin-Madison Biocore Program is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.