SAT & ACT Complete Grammar Rules

Vocabulary-style study flashcards covering key SAT and ACT grammar concepts, punctuation rules, syntax, and usage rules.

Semicolons and Periods Rule

On the SAT and ACT, semicolons and periods are considered grammatically identical and are used between two independent clauses or before transitional adverbs like however, therefore, or moreover that start a clause.

Sentence Boundary Questions

Questions in which the beginning of one sentence appears to be part of the previous sentence, requiring careful reading all the way to the period to identify where clauses end.

Colons and Single Dashes Rule

Punctuation used to introduce lists and explanations that must always follow a complete main clause (independent clause) that logically sets up the following information.

FANBOYS

An acronym for the seven coordinating conjunctions: For, And, Nor, But, Or, Yet, So.

Comma Splice

An error that occurs when two independent clauses (full sentences) are joined together with only a comma, often involving comma + pronoun.

Dependent Clause

A sentence fragment that cannot stand on its own as a complete sentence and begins with a subordinating conjunction such as although, because, when, until, while, since, before, or after.

Continuators

Transitional words and phrases (e.g., in addition, moreover, in fact, for example) that add new ideas, reinforce previous concepts, or convey a sequence of events.

Cause-and-Effect Transitions

Transitional words and phrases (e.g., therefore, consequently, thus) indicating that an action or event is the direct outcome of a preceding action or event.

Contradictors

Transitional words and phrases (e.g., however, nevertheless, in contrast) that signal opposing or contrasting ideas.

Non-Essential Information

A clause, phrase, or word that can be removed from a sentence without altering its core meaning, set off by two commas, two dashes, or parenthetical marks.

Essential vs. Non-Essential Names & Titles

A name or title is essential (no commas) if removing it breaks the sentence's basic sense; it is non-essential (set off by two commas) if the sentence remains grammatically coherent without it.

Possessive Nouns

Nouns formed to show ownership: singular nouns add apostrophe + -s, regular plural nouns add an apostrophe after -s, and irregular plural nouns add apostrophe + -s.

Its vs. It's

Its is the possessive form of it (no apostrophe), while it's is the contraction for it is.

They're vs. Their vs. There

They're is the contraction for they are, their is the plural possessive form of they, and there refers to a place or location.

Who's vs. Whose

Who's is the contraction for who is, while whose is the possessive form of who (which can apply to both people and objects/places).

Who vs. Whom

Who is used as a subject before a verb, whereas whom is used as an object following a preposition.

Subject-Verb Agreement

The rule requiring verbs to match their subjects in number: singular 3rd person verbs end in -s (e.g., it works), whereas plural 3rd person verbs do not end in -s (e.g., they work).

Present Perfect Tense

A verb construction formed by has or have + past participle to indicate an action that began in the past and continues into the present, typically signaled by for or since.

Past Perfect Tense

A verb construction formed by had + past participle used when describing two past actions to specify the one that happened first, required when using the phrase by the time.

Passive Voice

A grammatical construction where the subject and object are inverted (X did Y becomes Y was done by X), often creating wordy or awkward phrasing.

Parallel Structure

The principle requiring all items in a list, pair, or comparison to follow the same grammatical form (e.g., noun, noun, and noun).

Dangling Modifier

A grammatical error that occurs when an introductory descriptive phrase is not immediately followed by the specific noun or subject it describes.

Faulty Comparisons

An error involving the comparison of non-equivalent items (e.g., comparing a person to a thing), which is resolved by using phrases such as that of (singular) or those of (plural).

Shorter is Better (ACT)

An ACT rule stating that when multiple choices express the same essential meaning grammatically, the shortest and least redundant option is correct.

Comparatives vs. Superlatives

Comparatives compare two items (-er or more), while superlatives compare three or more items (-est or most); double forms like more stronger or most strongest are grammatically incorrect.

Pronoun Case Rule (ACT)

A method to test compound pronoun cases by crossing out proper names or accompanying pronouns to isolate the pronoun and evaluate it by ear.

Register

The tone or level of formality in writing, where correct choices avoid being overly informal or excessively grandiloquent/pretentious.