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Full Analysis of SAT Grammar Rules: Which Are Most Important?


When you are planning your study approach for SAT Writing, it’s important to know where your time is best spent.

Which grammar rules are really the most important to learn? What can help you make the greatest improvement to your score?

Read on to find out exactly how much each grammar rule matters and how you can use this information on the test.


What kinds of questions are on SAT Writing?

SAT Writing follows an extremely predictable format. There are two Writing sections on the test. (Note: There are always two graded Writing sections, but some tests may have a third one that is experimental and ungraded.)

The first Writing section will be between Section 2 and Section 7, and the second will ALWAYS be Section 10.

In the first Writing section, you will have three question types.


#1: Improving Sentences 

The first, which accounts for questions 1 – 11, is Improving Sentences. You will be given a sentence with an underlined portion and 5 answer choices. The first answer choice, A, is always the same as what is given in the original sentence (or Correct As Is). The other answers will re-write the underlined portion of the sentence in various ways.




We have written a guide to the best way to approach Improving Sentences Questions.


#2: Identifying Sentence Errors

The second question type is Identifying Errors (questions 12 – 29). In this type of question, you will be given a sentence that has four underlined words or phrases labeled A – D. After the sentence you also have the option of E, which is “No Error”. You have to choose the underlined part of the sentence that has a grammar mistake, or decide that the sentence has no errors and is correct as it is written.




#3: Improving Paragraphs

The third question type is Improving Paragraphs, which is questions 30 – 35. This section is a little different. You may be asked a grammar question, which oftentimes will look a lot like the Improving Sentences questions. However, you also may be asked questions about style and logic, such as where sentences best fit in the paragraph or what transition to use, and you can also be asked about the author’s rhetorical strategy.




This is how you should attack the Improving Paragraphs section.

Section 10 consists of 14 questions which are always Improving Sentences.

So to summarize, this is what the breakdown of different question types looks like:




But what concepts are tested? And why should you care?

Almost as predictable as the question types are the grammar rules that SAT Writing will test you on.

SAT Writing heavily favors a few main grammar rules, and lightly touches on a multitude of others.


Why should this matter to you?

This means that especially if you are aiming for a score in the 500 – 700 range, you should focus your studying on the main grammar rules that are covered.

In fact, many of the rules the SAT covers are so infrequently seen that there is a good chance that your test may not cover them at all.

I analyzed almost 700 SAT Writing questions from 14 official SAT tests, and wrote down the grammar concepts tested in each. For most SAT questions, the answer is fairly obvious if you know one main grammar rule. Occasionally, however, more than one rule is tested in the same question. In these circumstances, I counted the question for both grammar rules.


And the winners are…

The overwhelming winner of the frequency test is verb tense and form. Using the correct form of the verb can mean quite a few different things, including whether or not verbs are used consistently throughout the sentence, knowing when to use gerunds and avoiding them when they are unnecessary, when to use the infinitive, when to use certain tenses, and when past participles are appropriate.

These concepts make up over a whopping 20% of the questions in the Improving Sentences and Identifying Errors sections of the test.

Not far behind in second place are questions dealing with correct use of pronouns. These questions make up 12.5% of the questions in Improving Sentences and Identifying Errors.

These concepts include missing and ambiguous antecedents, pronoun case, and making sure that pronouns match their antecedents in number.

We have a three-way tie for third place. Subject-Verb Agreement, Run-ons and Fragments, and Parallel Structure each weigh in at around 9.5% of the questions asked.

If you master these five concepts, you will have all the information you need to over 60% of the questions on SAT Writing.


The full breakdown 

Here is the analysis of the most commonly-tested grammar concepts on SAT Writing, along with brief explanations of what each grammar rule means.




#1: Correct Verb Tense and Form: 20.5%

  •         Verbs tenses are used consistently and correctly throughout the sentence
  •         Gerunds are only used when necessary
  •         Infinitives are used correctly
  •         Tenses of verbs are formed correctly
  •         Past participles are not confused with past tense
  •        Wordiness with gerunds

To master this section, see our guide on how verbs are used on SAT Writing.


#2: Correct Pronouns and Antecedents: 12.5%

  •         Missing and ambiguous antecedents
  •         Correct use of singular and plural pronouns
  •         Pronoun case
  •         Pronoun-antecedent agreement
  •         “He or she” vs. “they”

See our guides on pronoun case and pronoun agreement to master these concepts.


#3: Subject-Verb Agreement: 9.5%

  •         Matching singular subjects with singular verbs and plural subjects with plural verbs
  •         Sentences with verbs before subjects
  •         Sentences with non-essential clauses or prepositional phrases between subject and verb

See this guide to subject-verb agreement.


#3: Parallel Structure: 9.5%

  •         Items in a list are phrased the same way
  •         Phrases connected by a conjunction have the same structure

See our guide to parallel structure on SAT Writing for more on this topic.


#3: Fragments and Run-ons: 9.5%

  •         Joining independent clauses incorrectly
  •         Missing subject and/or verb
  •         Recognizing non-essential or dependent clause vs. independent clause
  •         Correct use of semicolons and commas

This guide breaks down how to recognize and fix run-ons and fragments on SAT Writing.


#6: Misplaced and Dangling Modifiers: 7%

  •         Descriptive phrases must be next to the word they describe

See the guide to modifiers here.


#7: Idioms, Preposition use, and Diction: 6%

  •         Knowing which preposition is idiomatically correct in a phrase
  •         Recognizing commonly-confused words

This guide will teach you all about idioms on the SAT Writing, and here is a guide to diction and word choice.


#8: Faulty Comparisons: 4%

  •         Comparing two unlike things

See the guide to faulty comparisons here.


#10: Logical conjunction use: 3%

  •         Using conjunctions correctly according to their meaning: e.g., “but” for contrast, “and” for similarity, etc.

See more about conjunctions in our complete parts of speech guide.


#10: Word pairs: 3%

  •         Properly completed word pairs, e.g. either…or, neither…nor, not only…but also, between…and, just as…so


#10: Adjective vs. Adverb: 3%

  •         Using adjectives to describe nouns, and adverbs to describe adjectives, verbs, and adverbs

See the guide to adjectives and adverbs on SAT Writing here.


The above concepts make up 87.5% of the questions on SAT Writing.


What about that other 12.5%?

In addition to the above, master the following topics if you are aiming for an 800 on SAT Writing. The following concepts each make up less than 2.5% of the questions on SAT Writing, and many of them will not appear on any given test.


#11: Active or Passive voice: 2.2%

  •         Using the active voice when possible to avoid wordiness
  •         Passive voice used to correct dangling modifier or in certain constructions


#12: Correct relative pronouns: 2%


#13: Noun agreement: 1.5%

  •         Match singular subjects with singular predicate nominatives, and plural subjects with plural predicate nominatives
  •         For example: John is a scientist. John and Maria are scientists.


#14: Comparative vs. Superlative: 1%

  •         Comparative used for comparing two things, superlative used for three or more
  •         Correct formation of comparative and superlative


#15: Redundancy: 0.8%


#16: Other: 5%

  •         These concepts are tested so infrequently that it would be pointless to give them their own category
  •         These questions are very unpredictable.
  •         They can include: “noun is because” structure, “the reason is that”, comma used between subject and verb, general awkwardness, and many more miscellaneous topics


How can you use this information?

You should use  the information above to target your studying.

The first step here is to understand what kind of SAT score you are aiming for in order to get into the colleges you are applying to. If you haven’t figured this out yet, take some time to do that first.


For Low Scorers

If you are currently getting a low score on the SAT Writing, you should use the list above as a checklist to master one grammar concept at a time.

Start with Verb Tense and Form, and work your way down.

Keep in mind that if you manage to completely master just the first 6 grammar concepts listed above (Verb Tense through Misplaced Modifiers), you will be able to answer close to 70% of the grammar questions on the test correctly.

After you have reviewed these concepts, take a practice test. When you correct it, make sure you note what kind of questions you have missed.

(Note: If you have The Official SAT Study Guide, you can use their online resource to find answers to the questions, or you can use the appendices in Erica Meltzer’s The Ultimate Guide to SAT Grammar to check which question types you are missing.)

If you are missing questions based on the top 6 topics, go back and focus all of your study time on just those question types before moving on.


If you want a mid-range score…

If you are aiming for a mid-level score (500 – 650), you should focus your attention on learning the grammar concepts that make up the top 87.5% of the questions and ignore the concepts that make up the trickier 12.5% of the test.

If you get 87% of the questions correct on SAT Writing, and get a 7 or above on the essay, most curves will put you score in the 500 – 650 range.

Take practice tests to check that you have mastered concepts #1 – 10. If you are able to answers those questions comfortably, move on to the more obscure topics.


If you are aiming for a high score…

You will need to study all of the concepts listed above.

The grammar concepts that appear infrequently, such as noun agreement and relative pronoun use, individually don’t count for much. However, enough mistakes in these areas could quickly add up to give you a lower score than you are aiming for.

Once you have a good grasp on all of the concepts, you may want to add a bit of strategy to your game to make the test easier to conquer. You can do this by breaking down the test even further and understanding where you will see each type of question so that you know what to expect.

Fortunately, I’ve done that work for you.


Not All Question Types are Equal

The above percentages correspond to the grammar concepts tested across all three question types on SAT Writing, taken as a whole.

However, what if we were to break the test down by question type?

Though most of the grammar concepts listed above will appear in all of the question types, there are a few grammar concepts that will only appear in certain question types.

Others will heavily appear in a certain type of question.

Let’s look at the Improving Sentences questions first.




As you can see, there are a few concepts that make up a majority of the questions in Improving Sentences:

  • Correct Verb Tense and Form (including gerund use)
  • Sentence Fragments and Run-ons
  • Parallel Structure
  • Misplaced and Dangling Modifiers
  • Correct Pronoun and Antecedent Use


There are also some question types that will almost never appear on the Improving Sentences sections.

They include:

  • Adjectives vs. Adverbs
  • Relative Pronoun Errors
  • Noun Agreement
  • Comparative vs. Superlative


Now let’s look at Identifying Errors.




Again, a few question types make up the majority here:

  • Correct Verb Tense and Form
  • Subject-Verb Agreement
  • Correct Pronoun and Antecedent Use


And the question types you will almost never see include:

  • Sentence Fragments and Run-ons
  • Active vs. Passive
  • Redundancy
  • Misplaced and Dangling Modifiers


How can you use this information?

You can use this knowledge of the test to help anticipate what grammar concepts you will see in each type of question.

When you approach an Identifying Errors or Improving Sentences question, always look for the most common grammar mistakes first.

For example, when you know that over 70% of the Improving Sentences questions will have one of the top five errors listed above, you will have a much better idea what kind of answers to look for, and it will also help you make more educated guesses.


What about the Improving Paragraphs section?

This section tests the same grammar rules as Improving Sentences.

However, this section also tests several rules that don’t really fall into the grammar category. Instead, they are based on style and logic, and being able to understand how words and sentences work together in the context of a paragraph.

This section will also occasionally test rhetorical strategy. This means that you may be asked what the purpose of a paragraph or sentence is.

Here are the types of questions you will see on this section of the test:




  •         Sentence Revision (exactly like Improving Sentences): 33%
  •         Sentence insertion or deletion: 22%
  •         Using transitions: 15%
  •         Rhetorical strategy: 11%
  •         Information or word insertion: 7%
  •         Combining sentences: 7%
  •         Sentence order: 2%
  •         Paragraph division: 2%


What does this mean for you?

Keep in mind that Improving Paragraphs only make up 6 questions on every test.

That means that even if you can’t figure out any of the style, logic, and rhetorical strategy questions, but ace the grammar, you will only be missing about 4 questions on the whole SAT Writing.

Students aiming for a high score obviously will not want to write off four whole questions.

However, if you are aiming for a lower score, you should use your study time wisely by focusing on the grammar concepts listed above instead of worrying about the extra question types that only appear in the Improving Paragraphs section.


What about “No Error” and correct as is?




On the Improving Sentences section, answer A is always the same as what’s given to you in the original sentence – meaning if you choose this, you are saying the sentence is correct as is.

In Identifying Errors, answer E means there is no error. 


How often will you see these?

Taken as a whole, you will see these answers about 15% of the time.

You are slightly more likely to get a no error answer in Identifying Errors (19%) than in Improving Sentences (12.5%).

So if you are completing one of these sections and you don’t have any of these answers, know you’ve gone wrong somewhere!

Though some questions don't contain an error, they still test you on the above grammar concepts —  by seeing if you can tell when they are being used correctly.

We have a full article on the No Error answer here.


What would the statistically perfect test look like?




Now that we know everything about how the test breaks down by each question type and grammar concept, let’s see what a theoretically perfect test would look like.

Of course, no real SAT would follow these figures exactly, but it’ll give you a decent idea of what to expect.

Use this "Perfect Test" list to help guide your studying. After you take a practice test, take note of what kind of questions you have missed. Compare your notes to this list, and start off tackling your problem areas that appear highest up.


Improving Sentences: 25 Questions Total

6 questions on Correct Verb Tense and Form

4 questions on Fragments and Run-ons

3 questions on Parallel Structure

3 questions on Misplaced and Dangling Modifiers

3 questions on Correct Pronouns and Antecedents

1 question on Subject-Verb Agreement

1 question on Logical Conjunctions

1 question on Faulty Comparisons

1 question on Correct Use of Active and Passive

1 question on Word Pairs

1 question on Miscellaneous Topics


Identifying Errors: 18 Questions Total

4 questions on Correct Verb Tense and Form

3 questions on Correct Pronouns and Antecedents

3 questions on Subject-Verb Agreement

1 question on Idiom, Preposition Use, and Diction

1 question on Parallel Structure

1 question on Faulty Comparisons

1 question on Word Pairs

1 question on Adjectives vs. Adverbs

1 question on Noun Agreement

1 question on Comparative vs. Superlative

1 question on Miscellaneous Topics


Improving Paragraphs: 6 Questions Total

2 questions on Sentence Revision (Improving Sentences)

1 question on Sentence Insertion or Deletion

1 question on Using Transitions

1 question on Rhetorical Strategy

1 question on either Combining Sentences OR Word or Information Insertion


You would have about seven questions with the answer “No Error” or Correct As Is.


What’s next?

Now you know exactly what is on SAT Writing. Use the above links to master each topic.

All too much for you to handle? Never fear, there are some schools out there who don’t care about SAT Writing at all! 

If you are aiming to improve a low grade, see our article on how to score a 600 on SAT Writing.

If you are aiming for an 800, you will need to master all of the above concepts, even the infrequently used ones. See our article on top tips for scoring an 800 on SAT Writing.


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Mary Ann Barge
About the Author

Mary Ann holds a BA in Classics and Russian from the University of Notre Dame, and an MA from University College London. She has years of tutoring experience and is also passionate about travel and learning languages.

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