Model Comparison: Conventions of Standard English

═══════════════════════════════════════

Gemini 3 Pro

═══════════════════════════════════════

What You Need to Know

• This is the heavyweight category: "Conventions of Standard English" accounts for roughly 51–56% of the ACT English score. Mastering these rules is the fastest way to improve your composite score.
• Grammar is logic, not feeling: Rely on rigid structural rules (e.g., subject-verb agreement, punctuation hierarchy) rather than what "sounds good."
• Conciseness is key: When multiple answers are grammatically correct, the ACT almost always prefers the shortest, simplest option.
• Punctuation changes meaning: Commas, colons, and dashes dictate how a sentence is read. If the punctuation doesn't serve a specific grammatical function, it shouldn't be there.

Sentence Structure and Boundaries

This section governs how clauses are built and connected. The ACT loves to test your ability to distinguish between a complete sentence and a fragment or run-on.

Independent vs. Dependent Clauses

• Independent Clause: A group of words with a subject and a verb that expresses a complete thought (e.g., The test is difficult.).
• Dependent Clause: Contains a subject and verb but starts with a subordinating conjunction (e.g., because, although, when, if), making it incomplete on its own (e.g., Although the test is difficult).

Run-On Sentences and Comma Splices

A run-on sentence fuses two independent clauses with no punctuation. A comma splice incorrectly joins two independent clauses with only a comma.

Incorrect: I love science, I want to be a biologist. (Comma Splice)
Incorrect: I love science I want to be a biologist. (Run-On)

Four Ways to Fix It:

1. Period: I love science. I want to be a biologist.
2. Semicolon: I love science; I want to be a biologist.
3. Comma + FANBOYS: I love science, and I want to be a biologist. (FANBOYS = For, And, Nor, But, Or, Yet, So)
4. Subordination: Because I love science, I want to be a biologist.

Sentence Fragments

A fragment masquerades as a sentence but lacks a subject, a verb, or a complete thought.

• Example: Resulting in a significant change in scores. (Lacks a subject and finite verb)
• Fix: Connect it to an independent clause or add the missing elements.

Parallel Structure

Items in a list, comparison, or compound structure must share the same grammatical form.

• Incorrect: She likes running, swimming, and to hike.
• Correct: She likes running, swimming, and hiking.

Coordination and Subordination

• Coordination connects ideas of equal importance (using FANBOYS).
• Subordination emphasizes one idea over another (using words like because, since, while).
• Rule: Do not use both a coordinating and subordinating conjunction for the same clause structure. (e.g., Although I was tired, but I kept working is incorrect. Remove but).

Exam Focus

• Why it matters: These questions appear frequently and often involve simply changing punctuation marks.
• Typical question patterns: You will see a long sentence underlined. The options will offer different punctuation marks (period vs. semicolon vs. comma). If the words on both sides of the punctuation are independent sentences, a simple comma is always wrong.
• Common mistakes:
  • Assuming a long sentence is a run-on. Length does not determine structure.
  • Thinking "However" is a conjunction. You cannot join sentences with just a comma and "however"; you need a semicolon (e.g., It was raining; however, we played soccer.).

Punctuation Mechanics

Commas

Commas are the most frequently tested punctuation mark. Use them for:

1. Separating Items in a List: I bought apples, bananas, and pears. (The Oxford comma is preferred on the ACT).
2. Introductory Phrases: After the game, we went home.
3. FANBOYS: Before a coordinating conjunction connecting two independent clauses.
4. Non-Essential Clauses: Surround information that can be removed without changing the sentence's core meaning. My brother, a dentist, lives in Ohio.

Do NOT use commas:

• Between a subject and its verb.
• Before a prepositional phrase at the end of a sentence.
• Between an adjective and a noun (e.g., a bright, red car is wrong; a bright red car is correct if the adjectives are cumulative).

Semicolons and Colons

• Semicolon (;): Functionally identical to a period. Use it to separate two related independent clauses.
• Colon (:): Used to introduce a list, an explanation, or a quote.
  • The Golden Rule: The clause before the colon must be a complete independent sentence. The part after can be a fragment or a sentence.
  • Correct: I have one goal: to pass this test.
  • Incorrect: My list includes: paper, pens, and pencils. (The part before the colon is not a complete sentence).

Dashes and Parentheses

• Dashes (—): Used for emphasis or an abrupt change in thought. Can function like parentheses (pairs) or a colon (single).
  • If you open a non-essential phrase with a dash, you must close it with a dash.
• Parentheses ( ): Enclose non-essential information. Technically, the sentence must be grammatically complete if you remove the text inside.

Apostrophes and Possessives

• Singular Possession: Add 's (e.g., the dog's bone).
• Plural Possession ending in s: Add only ' (e.g., the dogs' bones).
• Plural Possession not ending in s: Add 's (e.g., children's toys).
• It's vs. Its:
  • It's = It is (contraction).
  • Its = Possessive (like his or her).

Exam Focus

• Why it matters: Punctuation questions are purely mechanical. If you know the rules, these are "free" points.
• Typical question patterns:
  • Asking you to choose between a dash and a comma (match the opening punctuation).
  • Distinguishing between its, it's, and its' (Note: its' does not exist).
• Common mistakes:
  • Using a colon after "such as" or "including." This breaks the independent clause rule.
  • Confusing plural nouns with possessive nouns (e.g., The student's are happy is wrong; it should be students).

Usage and Agreement

Subject-Verb Agreement

Verbs must match their subjects in number (singular vs. plural).

• The Trap: The ACT hides the subject behind a "prepositional phrase sandwich."
• Example: The box [of chocolates] is heavy. (Ignore "of chocolates"; the subject is "box").
• Collective Nouns: Words like team, group, family are usually singular.

Pronoun-Antecedent Agreement

Pronouns must match the noun they replace (the antecedent).

• Incorrect: Every student should bring their book.
• Strict Grammar Note: While "their" is common for singular usage in modern English, the ACT often prefers his or her or rephrasing for singular antecedents, though singular "their" is becoming more accepted. Always check if the antecedent is singular or plural.

Pronoun Case and Reference

• Subjective Case (I, he, she, we, they, who): Performs the action.
• Objective Case (me, him, her, us, them, whom): Receives the action.
• Who vs. Whom:
  • Use Who if you can replace it with he/she/they.
  • Use Whom if you can replace it with him/her/them.
• Ambiguous Reference: A pronoun must clearly refer to one specific noun. If it's unclear who "he" refers to, you must replace the pronoun with the specific name.

Verb Tense and Consistency

• Keep tenses consistent within a time frame. If a paragraph starts in the past tense, stay in the past unless there is a clear time shift (e.g., Now, I am…).
• Perfect Tenses:
  • Had gone (Past Perfect): An action completed before another past action.
  • Have gone (Present Perfect): An action that started in the past and continues or has relevance now.

Exam Focus

• Why it matters: Agreement errors are easy to spot if you isolate the subject and verb, but hard if you read for speed/flow.
• Typical question patterns:
  • A sentence where the subject is five words away from the verb.
  • Sentences starting with "There is/are…" (The subject comes after the verb).
• Common mistakes:
  • Matching the verb to the nearest noun rather than the actual subject.
  • Confusing who (subject) and whom (object).

Modifiers and Word Choice

Adjective and Adverb Usage

• Adjectives modify nouns (The good dog).
• Adverbs modify verbs, adjectives, or other adverbs, usually ending in -ly (The dog behaved well; extremely fast).
• Comparative vs. Superlative:
  • Compare two things: better, more.
  • Compare three or more things: best, most.

Modifier Placement

A modifier must be placed directly next to the word it describes.

• Dangling Modifier: Walking down the street, the trees looked beautiful. (The trees were not walking).
• Correction: Walking down the street, I saw the beautiful trees.
• Misplaced Modifier: He nearly ate the whole pizza vs. He ate nearly the whole pizza.

Idiomatic Expressions and Prepositions

English idioms are fixed phrases. Logic doesn't apply; memory does.

• Correct: Curious about, consistent with, preoccupied with.
• Incorrect: Curious on, consistent at.

Exam Focus

• Why it matters: Dangling modifiers are a favorite ACT trap because they often sound conversational but are logically impossible.
• Typical question patterns:
  • A sentence starts with a descriptive phrase followed by a comma. You must verify that the subject immediately following the comma is the one doing the action.
  • Idiom questions often ask you to swap prepositions.
• Common mistakes:
  • Choosing "good" when "well" is needed.
  • Selecting a choice because it sounds fancy. Simple is usually better.

Quick Review Checklist

• Can you identify the subject and verb in a complex sentence?
• Do you know the difference between a semicolon and a colon?
• Can you list the FANBOYS and explain how they work with commas?
• Can you spot a dangling modifier and fix it?
• Do you know the rule for "It's" vs. "Its"?
• Can you identify non-essential clauses and punctuate them correctly?
• Do you know that a semicolon acts exactly like a period?
• Can you determine if a list needs to be parallel?
• Do you know when to use "who" versus "whom"?

Final Exam Pitfalls

1. The "No Change" Trap: About 20–25% of answers are "NO CHANGE." Do not be afraid to pick it, but don't pick it just because you are unsure.
2. The Redundancy Error: Avoid answers that repeat information. If the sentence says "The annual yearly report," it is wrong because "annual" and "yearly" mean the same thing.
3. The Semicolon/Period Equivalence: If two answer choices are identical except one uses a period and the other uses a semicolon (e.g., A: rain. We and B: rain; we), both are likely wrong. The ACT rarely asks you to choose between two grammatically identical correct options.
4. Being and Having: Answer choices containing the word being are frequently (though not always) incorrect on the ACT because they often create passive or wordy constructions.
5. Comma Splices with "However": Remember, words like however, therefore, and moreover are NOT conjunctions. You cannot use them to join sentences with just commas. You need a semicolon or period before them.
6. Pausing for Commas: Do not place a comma just because you pause when reading. Place a comma only if a rule requires it.

═══════════════════════════════════════

GPT 5.2 Pro

═══════════════════════════════════════

What You Need to Know

• ACT English questions in Conventions of Standard English test whether you can spot and fix errors in sentence structure, grammar/usage, and punctuation in short passages (typically with an underlined portion and answer choices including NO CHANGE).
• Prefer the choice that is grammatically correct, clear, and concise—and that matches the sentence’s intended meaning.
• Most “easy points” come from mastering a few recurring rules: complete sentences, comma/semicolon/colon use, agreement, pronouns, and modifier placement.

Sentence Structure and Formation

Sentence structure and formation is building a complete, logical sentence—often by correctly joining or separating ideas.

• A clause has a subject + verb; an independent clause can stand alone.
• Decide whether ideas should be one sentence (with proper joining) or two sentences.
• Example: The team practiced daily, and it improved. (two independent clauses joined correctly)

Exam Focus

• Why it matters: ACT heavily tests whether you can recognize complete clauses and choose the cleanest correct structure.
• Typical question patterns:
  • Choose the best revision for an underlined “sentence-level” chunk.
  • Decide whether to combine sentences or split them.
  • Fix awkward, tangled clause structure.
• Common mistakes:
  • Choosing an option that “sounds fine” but creates a fragment/run-on.
  • Overusing commas where a stronger join (semicolon/period) is required.

Run-On Sentences and Comma Splices

A run-on incorrectly joins independent clauses without proper punctuation/conjunction. A comma splice joins two independent clauses with only a comma.

• Fix options:
  • Period: I left. It was late.
  • Semicolon: I left; it was late.
  • Comma + FANBOYS: I left, for it was late.
  • Subordination: I left because it was late.

Exam Focus

• Why it matters: This is a core ACT “mechanics” skill—frequent and quick to test.
• Typical question patterns:
  • Underlined join between two clauses.
  • Choices alternate among comma/semicolon/period/conjunction.
• Common mistakes:
  • Using a comma alone between two complete sentences.
  • Adding a conjunction but keeping the wrong punctuation (e.g., semicolon + and).

Sentence Fragments

A fragment is an incomplete sentence (often a dependent clause or phrase punctuated like a complete sentence).

• Common fragment starters: because, although, when, which, that.
• Fix by:
  • Attaching it to an independent clause, or
  • Revising to make it independent.
• Example: Because the road was icy. → Because the road was icy, we drove slowly.

Exam Focus

• Why it matters: ACT checks whether you can identify a missing independent clause.
• Typical question patterns:
  • “NO CHANGE” keeps a fragment; other choices attach it.
  • Underlined dependent-clause punctuation.
• Common mistakes:
  • Keeping a “because/which” clause as a standalone sentence.
  • Fixing by adding words that still don’t create a subject-verb independent clause.

Parallel Structure

Parallel structure means items in a list or comparison match in grammatical form.

• Lists: to hike, to swim, and to bike (all infinitives)
• Comparisons: more careful than reckless (adjectives match)
• Correlative pairs: either/or, neither/nor, not only/but also must be parallel.

Exam Focus

• Why it matters: Parallelism is a high-yield clarity/grammar rule that appears in lists and paired constructions.
• Typical question patterns:
  • Fix mismatched list items.
  • Repair not only…but also structure.
• Common mistakes:
  • Mixing forms: running, to jump, and bikes.
  • Forgetting to make both sides of a comparison match.

Coordination and Subordination

Coordination joins equal ideas (often independent clauses). Subordination makes one idea dependent to show logic (cause, contrast, time).

• Coordination: comma + FANBOYS or semicolon.
• Subordination words: because, although, since, when, while, if.
• Example meaning shift:
  • I left, and it rained. (two facts)
  • I left because it rained. (cause)

Exam Focus

• Why it matters: ACT rewards choices that correctly show relationships between ideas.
• Typical question patterns:
  • Choose the best conjunction (and/but/so) or subordinating word.
  • Decide between semicolon vs dependent clause.
• Common mistakes:
  • Picking a connector that changes logic (e.g., but when no contrast exists).
  • Creating a fragment by subordinating without an independent clause.

Commas, Semicolons, and Colons

Commas separate elements; semicolons join related independent clauses; colons introduce explanations/lists after an independent clause.

• Comma uses:
  • After introductory elements: After the show, we left.
  • Around nonessential (parenthetical) info: The car, which is red, is mine.
  • Before FANBOYS joining two independent clauses.
• Semicolon: The test was hard; I studied anyway.
• Colon: She brought three items: pens, paper, and tape. (must have a complete clause before the colon)

Exam Focus

• Why it matters: Punctuation is a major part of this reporting category and often tested with minimal context.
• Typical question patterns:
  • Pick comma vs semicolon vs period.
  • Decide if a colon is legal after the words before it.
  • Essential vs nonessential clause comma decisions.
• Common mistakes:
  • Using a colon after an incomplete lead-in.
  • Using commas where semicolons/periods are required between two independent clauses.

Apostrophes and Possessives

An apostrophe shows possession or forms contractions.

• Possessive nouns:
  • Singular: the student’s book
  • Plural ending in s: the students’ books
  • Plural irregular: children’s games
• Its (possessive) vs it’s (it is).

Exam Focus

• Why it matters: Apostrophe errors are quick-edit targets—common and easy to test.
• Typical question patterns:
  • its/it’s choice.
  • singular vs plural possession.
• Common mistakes:
  • Using apostrophes for plurals (apple’s).
  • Confusing its and it’s.

Dashes and Parentheses

Dashes (—) and parentheses ( ) set off extra information; they must be used consistently.

• Use two dashes/parentheses to open and close an interruption.
• Dashes are stronger than commas; parentheses are more “aside.”
• Example: My brother—an excellent cook—made dinner.

Exam Focus

• Why it matters: ACT tests whether punctuation matches the boundaries of the inserted phrase.
• Typical question patterns:
  • Fix mismatched punctuation (one dash but not the other).
  • Choose commas vs dashes vs parentheses around nonessential info.
• Common mistakes:
  • Mixing marks: (phrase— or —phrase),.
  • Using interrupting punctuation around essential information (changing meaning).

Subject-Verb Agreement

Subject-verb agreement means the verb matches the subject in number (singular/plural).

• Ignore interrupting phrases: The bouquet of roses smells lovely.
• Common tricky subjects:
  • Either/neither (usually singular): Neither is ready.
  • Each/everyone (singular): Each has a ticket.
  • There is/there are: verb agrees with the real subject: There are many reasons.

Exam Focus

• Why it matters: Agreement is a classic ACT grammar target, often with distracting prepositional phrases.
• Typical question patterns:
  • Underlined verb form choices (is/are, has/have).
  • Long subjects with “of,” “along with,” “as well as.”
• Common mistakes:
  • Matching the verb to the nearest noun instead of the subject.
  • Treating each or everyone as plural.

Pronoun-Antecedent Agreement

A pronoun must agree with its antecedent (the noun it replaces) in number and (when relevant) gender.

• Singular antecedent → singular pronoun: Each student turned in his or her work (ACT may also accept a clear rewrite to plural: All students turned in their work if the sentence is revised accordingly).
• Watch indefinite pronouns: everyone, somebody, each (singular).

Exam Focus

• Why it matters: ACT tests clarity and grammatical consistency, especially with indefinite pronouns.
• Typical question patterns:
  • Fix each…their mismatches.
  • Choose between singular/plural pronouns.
• Common mistakes:
  • Letting a nearby plural noun “pull” the pronoun plural.
  • Creating awkwardness by forcing agreement instead of rewriting cleanly.

Pronoun Case and Reference

Pronoun case depends on function: subjective (I/he/she/we/they), objective (me/him/her/us/them), possessive (my/his/her/our/their).

• Subject: She and I are leaving.
• Object: The coach called him and me.
  Pronoun reference must be clear—no ambiguous “this/that/which/it.”
• Ambiguous: When Alex texted Jordan, he was upset. (Who?)

Exam Focus

• Why it matters: ACT rewards precision; unclear pronouns can make a sentence logically wrong.
• Typical question patterns:
  • I vs me (often in compound phrases).
  • Fix unclear this/that/it/which.
• Common mistakes:
  • Overcorrecting to I in object position (between you and I is wrong).
  • Leaving a pronoun with multiple possible antecedents.

Verb Tense and Tense Consistency

Verb tense locates action in time; tense consistency keeps tenses aligned unless the timeline truly changes.

• Past narrative stays past: She walked in and greeted everyone.
• Use present perfect for actions continuing to present: has lived.
• Watch sequence of tenses with time markers (then, now, since, by the time).

Exam Focus

• Why it matters: ACT often embeds one wrong-tense verb in an otherwise consistent passage.
• Typical question patterns:
  • Choose among walked/walks/has walked/had walked.
  • Fix a sudden tense shift within a paragraph.
• Common mistakes:
  • Switching to present tense in a past-tense story (or vice versa) without reason.
  • Choosing perfect tenses (had done) when no “earlier past” is established.

Adjective and Adverb Usage

Adjectives modify nouns; adverbs modify verbs/adjectives/adverbs (often ending in -ly).

• real (adj) vs really (adv): really fast
• Comparative forms:
  • Two items: better/worse, more/less
  • Three+ items: best/worst, most/least
• Tricky: good (adj) vs well (adv; also health).

Exam Focus

• Why it matters: These questions test whether modifiers match what they modify and standard comparative forms.
• Typical question patterns:
  • Choose bad/badly, real/really.
  • Fix faulty comparisons (more better).
• Common mistakes:
  • Using an adjective to modify a verb (She sings beautiful).
  • Using double comparatives/superlatives (most fastest).

Modifier Placement

A modifier (word/phrase/clause describing something) must be placed next to what it modifies.

• Misplaced modifier: She served sandwiches to the children on paper plates. (Children on plates?)
• Dangling modifier: the implied subject doesn’t match: Walking to school, the rain soaked my backpack. (Rain wasn’t walking.)
• Fix by moving the modifier or adding the correct subject.

Exam Focus

• Why it matters: ACT tests clarity and logic—modifier errors often create unintentionally funny or illogical meanings.
• Typical question patterns:
  • Reorder sentence parts for logical modification.
  • Choose a revision that adds the right subject after an introductory phrase.
• Common mistakes:
  • Keeping “-ing” openers without a clear doer.
  • Fixing grammar but not the meaning (still illogical).

Idiomatic Expressions and Preposition Usage

Idioms are standard, conventional word pairings (often with prepositions) that the ACT expects in formal edited English.

• Common preposition pairings:
  • different from (often preferred in formal usage)
  • capable of, responsible for, interested in
  • between (two) vs among (three+)
• Also test wordiness and “standard” phrasing: choose the most straightforward correct option.

Exam Focus

• Why it matters: ACT includes usage choices where only one option matches standard edited English.
• Typical question patterns:
  • Pick the correct preposition (of/in/for/to).
  • Choose concise idiomatic phrasing over wordy alternatives.
• Common mistakes:
  • Picking what you “hear” in casual speech rather than standard usage.
  • Changing meaning by swapping prepositions (agree with vs agree to can differ by context).

Quick Review Checklist

• Can you identify an independent clause and use it to test punctuation choices?
• Can you fix a run-on using a period, semicolon, comma + FANBOYS, or subordination?
• Can you spot and repair fragments starting with because/although/which?
• Can you enforce parallel structure in lists and correlative pairs (either/or, not only/but also)?
• Do you know when to use a comma vs semicolon vs colon?
• Can you apply subject-verb and pronoun-antecedent agreement with distracting phrases?
• Can you choose correct pronoun case (I/me, who/whom) and ensure clear reference?
• Can you keep verb tense consistent with the passage timeline?
• Can you fix misplaced/dangling modifiers so the meaning is logical?
• Can you recognize common idioms/preposition pairings and choose the most concise standard option?

Final Exam Pitfalls

1. Comma splice trap: If both sides are independent clauses, don’t choose “comma only”—use a period, semicolon, or comma + coordinating conjunction.
2. Colon misuse: Don’t put a colon after an incomplete setup; ensure there’s a full independent clause before the colon.
3. Agreement distractions: Don’t match the verb/pronoun to the nearest noun—match it to the true subject/antecedent.
4. Dangling opener: If a sentence starts with an introductory modifier, the next noun must be the doer; otherwise revise the subject.
5. Ambiguous pronoun: Avoid choices where it/this/which could refer to multiple nouns—pick or create a clear antecedent.

═══════════════════════════════════════

Claude Opus 4.6

═══════════════════════════════════════

What You Need to Know

• Conventions of Standard English questions make up roughly 50–60% of the ACT English test (about 30–35 of the 75 questions). Mastering grammar, punctuation, and sentence structure is the single highest-yield investment you can make for this section.
• The ACT never asks you to name a grammar rule. Instead, it tests whether you can identify and fix errors embedded in passages. Every question gives you an underlined portion and asks you to choose the best revision (or "NO CHANGE").
• Conciseness is king on the ACT. When two answer choices are grammatically correct, the shorter, clearer option is almost always right.
• Most errors fall into predictable patterns: comma splices, pronoun agreement, verb tense shifts, and misplaced modifiers. Learning to spot these patterns quickly will save time and boost your score.

Sentence Structure and Formation

Sentence structure refers to how clauses and phrases are arranged to create complete, grammatically correct sentences. Every complete sentence needs a subject and a predicate (verb) and must express a complete thought.

The ACT tests your ability to distinguish between:

• Simple sentences: one independent clause
• Compound sentences: two independent clauses joined correctly
• Complex sentences: an independent clause + one or more dependent clauses
• Compound-complex sentences: a combination of the above

Run-On Sentences and Comma Splices

A run-on sentence (fused sentence) joins two independent clauses with no punctuation or conjunction. A comma splice joins them with only a comma—no conjunction.

Four ways to fix these errors:

1. Period: The team won. They celebrated.
2. Semicolon: The team won; they celebrated.
3. Comma + coordinating conjunction: The team won, and they celebrated.
4. Subordination: After the team won, they celebrated.

Sentence Fragments

A sentence fragment lacks a subject, a verb, or a complete thought. Common fragment traps on the ACT:

• Dependent clauses standing alone: Because she studied all night.
• Participial phrases posing as sentences: Running through the park at sunrise.
• Appositives without a main clause: A talented musician with years of experience.

Fix fragments by attaching them to a nearby independent clause or by adding the missing element.

Exam Focus

• Why it matters: Sentence boundary errors appear on nearly every ACT English test—expect 3–5 questions.
• Typical question patterns:
  • An underlined section connects two complete thoughts; you choose the punctuation/conjunction that correctly joins them.
  • A fragment is underlined and you must pick the revision that creates a complete sentence.
  • One answer choice is a run-on, one is a comma splice, one is a fragment, and one is correct.
• Common mistakes: Choosing a comma where a semicolon or period is needed; failing to recognize a dependent clause as a fragment.

Parallel Structure

Parallel structure means that items in a list, comparison, or paired construction use the same grammatical form.

• Incorrect: She likes hiking, to swim, and biking.
• Correct: She likes hiking, swimming, and biking.

Watch for parallelism with:

• Lists and series
• Correlative conjunctions: both…and, either…or, neither…nor, not only…but also
• Comparisons using than or as

Exam Focus

• Why it matters: Parallel structure questions are easy points once you know the pattern—expect 1–3 per test.
• Typical question patterns: A list or paired construction is underlined; one answer matches the grammatical form of the other items.
• Common mistakes: Mixing gerunds and infinitives in a series; ignoring the structure that precedes the underlined portion.

Coordination and Subordination

Coordination joins ideas of equal importance using coordinating conjunctions (FANBOYS: for, and, nor, but, or, yet, so) or semicolons.

Subordination makes one idea dependent on another using subordinating conjunctions (because, although, since, when, if, while) or relative pronouns (who, which, that).

The ACT tests whether you choose the logical connector. Ask: Are these ideas contrasting, causal, or additive?

Exam Focus

• Why it matters: These questions test logic as much as grammar—expect 2–4 per test.
• Typical question patterns: You choose between connectors like however, therefore, because, and although for an underlined transition.
• Common mistakes: Using because where although is needed (mixing up cause and contrast); creating a comma splice by using a conjunctive adverb (however) with only a comma.

Commas, Semicolons, and Colons

Commas

Use commas to:

• Separate items in a list of three or more (the ACT accepts the Oxford comma)
• Set off nonessential/nonrestrictive information: My brother, who lives in Texas, is visiting.
• Follow introductory elements: After the storm, we surveyed the damage.
• Separate independent clauses joined by a FANBOYS conjunction
• Do NOT use a comma between a subject and its verb or between a verb and its object

Semicolons

• Join two related independent clauses: She studied hard; she earned an A.
• Use before conjunctive adverbs (however, therefore, moreover) with a comma after: She studied hard; therefore, she earned an A.

Colons

• Introduce a list, explanation, or elaboration after a complete sentence: She packed three items: a tent, a stove, and a lantern.
• What comes before a colon must be an independent clause.

Exam Focus

• Why it matters: Punctuation questions are the most frequently tested conventions category—expect 8–12 questions.
• Typical question patterns: Choosing between comma, semicolon, colon, and no punctuation for an underlined spot; deciding whether a clause is essential (no commas) or nonessential (commas).
• Common mistakes: Putting a comma before that (restrictive clauses don't get commas); using a semicolon before a dependent clause; placing a colon after an incomplete sentence.

Apostrophes and Possessives

• Singular possessive: the dog's collar
• Plural possessive: the dogs' collars
• Its vs. it's: its = possessive; it's = it is/it has
• Who's vs. whose: who's = who is; whose = possessive

Apostrophes are never used to form simple plurals.

Exam Focus

• Why it matters: Expect 1–3 questions; these are quick wins if you know the rules.
• Typical question patterns: Choosing between its/it's, their/they're/there, or singular vs. plural possessive forms.
• Common mistakes: Confusing it's with its; adding an apostrophe to a plural noun that isn't possessive.

Dashes and Parentheses

Em dashes (—) and parentheses set off nonessential information. If you open with a dash, you must close with a dash (unless the aside ends the sentence). The same logic applies to parentheses.

• My neighbor—an accomplished pianist—performed at the gala.
• Dashes provide emphasis; parentheses are more of an aside.

Exam Focus

• Why it matters: Expect 1–2 questions testing matched pairs of dashes or parentheses.
• Typical question patterns: One dash is given; you must find the answer that uses a second dash (not a comma or parenthesis) to close the aside.
• Common mistakes: Mixing a dash with a comma to set off the same phrase; forgetting that the punctuation marks must match.

Subject-Verb Agreement

The verb must agree in number with its subject, not with a nearby noun.

• The box of chocolates is on the table. (subject = box)
• Compound subjects joined by and take a plural verb: The cat and the dog are playing.
• With or/nor, the verb agrees with the nearer subject: Neither the teacher nor the students were ready.
• Watch for inverted sentences: There are many reasons…

Exam Focus

• Why it matters: Expect 2–4 questions; the ACT loves to separate the subject from the verb with a long prepositional phrase.
• Typical question patterns: A plural noun in a prepositional phrase sits next to the verb, tempting you to pick a plural verb when the actual subject is singular.
• Common mistakes: Agreeing the verb with the object of a preposition; missing that each, every, everyone, and nobody are singular.

Pronoun-Antecedent Agreement

A pronoun must agree in number and person with its antecedent (the noun it replaces).

• Each student must bring his or her own calculator. (singular)
• Collective nouns (team, jury, committee) are typically singular on the ACT.

Pronoun Case and Reference

Pronoun case means choosing the correct form:

• Subjective: I, he, she, we, they, who
• Objective: me, him, her, us, them, whom
• Possessive: my, his, her, our, their, whose

Tip: Remove the other person to test case — She and I went → I went ✓ (Me went ✗).

Pronoun reference means each pronoun must clearly refer to one specific antecedent. An ambiguous pronoun has more than one possible antecedent.

Exam Focus

• Why it matters: Pronoun questions appear 2–4 times per test.
• Typical question patterns: Choosing between who/whom; identifying whether they has a clear singular or plural antecedent; picking the option that eliminates ambiguity.
• Common mistakes: Using them to refer to a singular noun; choosing who where whom is correct (and vice versa); leaving an ambiguous this or it with no clear antecedent.

Verb Tense and Tense Consistency

The ACT tests whether you use the correct tense and maintain consistency within a passage.

• Don't shift tenses without a reason.
• Use past perfect (had + past participle) for an action completed before another past action.
• Use present perfect (has/have + past participle) for actions that started in the past and continue to the present.

Exam Focus

• Why it matters: Expect 2–3 questions; the passage's surrounding context determines the correct tense.
• Typical question patterns: The underlined verb is in a different tense from the rest of the paragraph; you choose the tense that matches.
• Common mistakes: Switching to present tense in a past-tense narrative; confusing simple past with past perfect.

Adjective and Adverb Usage

• Adjectives modify nouns: a quick runner
• Adverbs modify verbs, adjectives, or other adverbs: She runs quickly.
• Use adjectives after linking verbs (is, seems, feels): She feels bad (not badly).

Modifier Placement

A misplaced modifier is too far from the word it modifies. A dangling modifier has no clear word to modify in the sentence.

• Dangling: Walking to school, the rain started. (Who is walking?)
• Corrected: Walking to school, I got caught in the rain.

Rule: The subject immediately after an introductory modifying phrase must be the person or thing performing that action.

Exam Focus

• Why it matters: Modifier questions appear 1–3 times per test and are easy to miss if you're not looking for them.
• Typical question patterns: An introductory participial phrase is followed by answer choices with different subjects—only one logically performs the action.
• Common mistakes: Choosing an answer where the subject doesn't match the modifier; placing an adjective where an adverb is needed.

Idiomatic Expressions and Preposition Usage

Idioms are fixed expressions that don't follow predictable rules—you either know them or you don't. The ACT tests common prepositional idioms:

Exam Focus

• Why it matters: Expect 1–2 idiom questions; these rely on familiarity rather than rules.
• Typical question patterns: The underlined preposition differs across answer choices; you select the one that sounds correct with the accompanying verb or adjective.
• Common mistakes: Choosing a preposition that "sounds okay" in casual speech but isn't standard; overthinking—if a phrase sounds natural and no grammar rule is broken, trust it.

Quick Review Checklist

• Can you identify and fix a run-on sentence or comma splice using at least three different methods?
• Can you spot a sentence fragment and attach it to an independent clause?
• Do you know the difference between essential (restrictive) and nonessential (nonrestrictive) clauses—and when to use commas?
• Can you use semicolons and colons correctly, ensuring what precedes them is an independent clause?
• Do you know the difference between its and it's, whose and who's?
• Can you find the true subject of a sentence even when prepositional phrases separate it from the verb?
• Can you identify a dangling or misplaced modifier and correct it by changing the subject?
• Do you know when to use who vs. whom?
• Can you maintain consistent verb tense throughout a paragraph?
• Can you ensure that items in a list or comparison use parallel grammatical forms?

Final Exam Pitfalls

1. Falling for the "sounds right" trap. Many comma splices and pronoun errors sound fine in everyday speech. Always apply the rules—check whether two independent clauses are joined correctly and whether every pronoun has a clear, matching antecedent.

2. Ignoring the surrounding sentences. Verb tense and pronoun reference questions require you to read the context—not just the underlined portion. Always read at least the full sentence before and after.

3. Matching the verb to the wrong noun. When a prepositional phrase sits between the subject and the verb (The collection of rare stamps is valuable), cross out the phrase mentally and match the verb to the true subject.

4. Mismatching paired punctuation. If one dash or parenthesis opens an aside, the same punctuation mark must close it. Don't mix a dash with a comma or a parenthesis.

5. Choosing a wordy option when a concise one is grammatically correct. The ACT rewards brevity. If two choices are both error-free, pick the shorter one—especially if it eliminates redundancy.

6. Picking "NO CHANGE" too often—or not often enough. "NO CHANGE" is correct roughly 25% of the time (it's one of four answer choices). Don't be afraid to select it, but don't default to it either. Evaluate every option.