# Grammar study guides

Canonical: https://duckyhelper.com/learn/grammar/
Updated: 2026-10-01

Fifteen short guides to the grammar and punctuation rules that cost students the most points in essays and on tests. Each one gives the rule in plain words, a table of wrong and right sentences, worked fixes, the most common mistakes, and five practice questions with full explanations. Where style guides disagree, such as the serial comma or James's versus James', the guide says so and shows both.

- [Comma rules](https://duckyhelper.com/learn/grammar/commas/): The comma rules that matter most, in plain words: before and or but, after intro words, in lists, around extra information. Examples and 5 practice questions.
- [When to use a semicolon](https://duckyhelper.com/learn/grammar/semicolons/): When to use a semicolon, in plain words: between two related sentences, before however or therefore, and in lists that already have commas. With practice.
- [How to use a colon](https://duckyhelper.com/learn/grammar/colons/): How to use a colon: after a complete sentence to introduce a list, an example or an explanation. When not to use one, plus colon vs semicolon, with practice.
- [Apostrophe rules](https://duckyhelper.com/learn/grammar/apostrophes/): Apostrophe rules in plain words: one owner, many owners, children's, contractions, and why plurals and its never take one. Examples and 5 practice questions.
- [Subject-verb agreement](https://duckyhelper.com/learn/grammar/subject-verb-agreement/): Subject-verb agreement in plain words: find the real subject, then match the verb. Tricky cases: of phrases, and, or, each, there is. With 5 practice questions.
- [Pronoun-antecedent agreement](https://duckyhelper.com/learn/grammar/pronoun-antecedent-agreement/): How to make pronouns agree with the nouns they replace: singular or plural, clear reference, no switching person. Examples, common mistakes and practice.
- [Misplaced and dangling modifiers](https://duckyhelper.com/learn/grammar/misplaced-and-dangling-modifiers/): What misplaced and dangling modifiers are, how to spot them, and the two ways to fix them. Clear examples, common mistakes and 5 practice questions.
- [Parallel structure](https://duckyhelper.com/learn/grammar/parallel-structure/): What parallel structure is and how to fix lists, comparisons and paired words like not only and but also so every part matches. Examples and 5 practice items.
- [Run-on sentences, comma splices and fragments](https://duckyhelper.com/learn/grammar/run-on-sentences-and-fragments/): How to spot and fix run-on sentences, comma splices and sentence fragments, with the four ways to join two sentences and clear examples. 5 practice items.
- [Who vs whom](https://duckyhelper.com/learn/grammar/who-vs-whom/): When to use who and when to use whom, with the he or him test, whoever vs whomever, and examples. Plus 5 practice questions with answers explained.
- [Its vs it's](https://duckyhelper.com/learn/grammar/its-vs-its/): Its vs it's explained simply: it's means it is or it has, its shows ownership. The one-second test, examples, common mistakes and 5 practice questions.
- [Affect vs effect](https://duckyhelper.com/learn/grammar/affect-vs-effect/): Affect vs effect made simple: affect is usually a verb, effect is usually a noun. The quick test, the two rare uses, examples and 5 practice questions.
- [Verb tense](https://duckyhelper.com/learn/grammar/verb-tense/): Verb tenses in plain words: past, present, future, the perfect tenses, staying consistent, and present tense for literature. Examples and 5 practice items.
- [Active vs passive voice](https://duckyhelper.com/learn/grammar/active-vs-passive-voice/): Active vs passive voice explained: how to spot passive voice, how to change it to active, and when passive is the better choice. Examples and 5 practice items.
- [Capitalization rules](https://duckyhelper.com/learn/grammar/capitalization/): Capitalization rules for students: proper nouns, titles before names, family words, school subjects, seasons, directions and regions. Examples and practice.

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