📝

ACT Grammar Rules Overview

Aug 13, 2025

Overview

This lecture covers all essential grammar rules needed for the ACT English section, focusing on punctuation, word choice, sentence structure, agreement, and style.

Punctuation Rules

  • Periods separate two complete, standalone sentences.
  • Commas indicate a brief pause but cannot connect two complete sentences (avoiding a comma splice).
  • Semicolons connect two related, complete sentences; a period can often be substituted.
  • Colons introduce lists, explanations, or descriptions, even for a single item, but not after "such as."
  • Single em dashes (—) work like colons; double em dashes set off info in the middle of a sentence, like parentheses.

Possessives & Commonly Confused Forms

  • Apostrophe before "s" shows singular possession (the girl’s sweater); after "s" shows plural possession (the boys’ game).
  • Its (no apostrophe) means possession; it's (with apostrophe) means "it is."
  • Test contractions by replacing them with their expanded forms.

Word Choice & Common Confusions

  • Accept (verb, to receive) vs. except (to exclude); effect (noun, result) vs. affect (verb, to influence); access (verb, to enter) vs. excess (noun, extra).
  • Proceed (to go forward) vs. precede (to come before); then (sequence) vs. than (comparison).
  • Use "whom" after a preposition; "who" as a subject.
  • Build academic vocabulary by looking up unfamiliar words during study.

Sentence Structure & Style

  • Prefer concise, simple sentences; remove redundancy and avoid passive voice.
  • When combining sentences, avoid multiple subjects for clarity.

Introductions, Transitions, Conclusions

  • Good introductions prepare the reader and require reading ahead.
  • Effective transitions reference the previous idea and connect to the next.
  • Conclusions summarize the main idea, often found in the first paragraph.

Evidence and Clarity

  • Support claims with relevant, specific evidence or data.
  • Define or give examples for technical terms if the reader may not know them.

Modifiers & Logical Order

  • Modifying/descriptive phrases must be next to the word they describe to avoid misplaced modifiers.
  • Ensure the logical flow of ideas by keeping related thoughts together (sentence sandwich method).

Agreement & Consistency

  • Match subject and verb in number (singular/plural).
  • Keep verb tense consistent unless context dictates otherwise.
  • Maintain formal, academic tone throughout; avoid conversational language.
  • Use parallel structure (keep lists and patterns consistent).
  • Compare only similar items (people to people, activities to activities).
  • Use matching pairs: not only/but also, either/or, neither/nor.

Key Terms & Definitions

  • Comma splice — error when two complete sentences are joined only by a comma.
  • Possessive — shows ownership (apostrophe placement is key).
  • Redundant — unnecessarily repetitive.
  • Modifier — a descriptive word or phrase.
  • Parallel structure — using the same grammatical format in a list or pattern.
  • Preposition — a word showing relationship between nouns (e.g., in, on, by).

Action Items / Next Steps

  • Practice applying these rules to ACT English practice questions.
  • Look up unknown words during daily reading to build vocabulary.
  • Refer to this cheat sheet when reviewing or doing ACT prep.