GMAT Tips - Verbal: Sentence Correction

The last section in the GMAT is the Verbal section and, along with Quant, calculates your raw score from 200-800. It consists of 41 questions divided across three types: sentence correction (SC), critical reasoning (CR), and reading comprehension (RC). One might assume that each question type would each receive a third of those 41 questions. In reality, however, sentence correction receives closer to 40%, with the other two topics splitting the remaining 60%.

This unequal weighting has its pros and cons. For one, since sentence correction questions take less time to answer than CR or RC, you can make up for lost time on other question types. On the other hand - and this can be especially true for non-native English speakers - SC is grammatically intimidating. In regards to sentence correction on the GMAT, perhaps the famous line from The Wizard of Oz should be changed to: “conjugation, pronouns, and idioms…oh my!”

While an above-average understanding of the English language is necessary to achieve success on sentence correction, this puzzle has more than one piece. When approaching SC questions, do your best ‘Weird Al’ Yankovic [a comedic songwriter] impression and “don’t go chasing grammar rules.”

Waterfalls – or in this case, logic – is more important. Below is a discussion on the strategy you’ll need to dominate SC. To wrap up, we’ll walk through one of the GMAT practice questions together.

Basic strategy

As with data sufficiency (DS), you’ll need a routine for SC - as you will for all strategy-heavy sections. The key to a good routine is that it’s efficient and repeatable. The following four steps are more compact than what other GMAT prep companies will recommend, but time is scarce on the GMAT, and so you should always err to the side of being terse. These four steps are really all you need:

1) Read the stimulus

2) Use logic to form 3-2 splits

3) Use RAMP [outlined below] to isolate the correct answer

4) Replace answer in the sentence and reread

First things first, you need to read the stimulus. How long is the sentence? What portion is underlined? Does it obviously ‘sound’ incorrect? After you complete the initial reading you should have an idea of the sentence’s errors. Generally, a SC question will have two major errors. These errors will form a decision point, which is a fancy way of saying ‘groups of similar answer choices’.

For example, if you see three answer choices in the past tense and two in the present tense, this is a decision point. After you identify these errors, split the answer choices along the decision point and use RAMP to eliminate the incorrect group. Then split again using logic and RAMP to isolate the correct answer. Before moving to the next question, replace the answer in the sentence to make sure it’s correct.

Advanced strategy 

On a simple SC question, you probably won’t have to use much more than logic to isolate the correct answer. On a difficult SC question, however, you’ll need a Swiss Army knife of strategy to do so. That do-it-all tool is called ‘RAMP’:  Each of these four letters stands for a common error hidden in GMAT’s SC questions. Once you’ve used logic to form decision points in Step 2, cycle through RAMP to isolate the correct answer.

Reference errors result when the sentence incorrectly refers to its subject with a pronoun. If it’s comparing one situation to another, ask yourself, does that make sense? Think of comparison errors as uneven ‘scales of justice’. They must - logically – be balanced on both sides. Similarly, parallelism errors are made when the ‘flow’ of a sentence isn’t consistent.

Agreement aims to determine if the subject/verb agree in number – singular vs. plural – and tense. Typically, the subject will come before the verb in a sentence. On more difficult questions, however, the GMAT will try to trick you by inverting the subject and the verb. Lastly, modifier errors occur when a phrase is adding detail to a sentence, but not in the intended way.

Putting It All Together

Let’s illustrate the routine and strategies discussed above with one of many GMAT practice questions:

Rock samples taken from the remains of an asteroid about twice the size of the 6-mile-wide asteroid that eradicated the dinosaurs has been dated to be 3.47 billion years old and thus is evidence of the earliest known asteroid impact on Earth.

a) has been dated to be 3.47 billion years old and thus is

b). has been dated at 3.47 billion years old and thus is

c)  have been dated to be 3.47 billion years old and thus are

d) have been dated as being 3.47 billion years old and thus

e) have been dated at 3.47 billion years old and thus are

On average, you shouldn’t take longer than one minute to answer a SC problem, so try to work with this timing in mind even as you study GMAT practice questions. Some questions you’ll know right away, but others will likely take you the full minute. The easiest way to waste time on SC is by rereading eliminated answer choices and irrelevant parts of the sentence:  e.g. useless modifiers. The GMAT is computerized, so you can’t physically cross out unnecessary words, but feel free to make notes on your scratch [scrap] paper.

Following the routine described above, when a question like the above pops up on your exam, your first step should be to read the stimulus. Pay special attention to the underlined portion, but overall, you just want to build a basic understanding of the question. While doing so, ask yourself:  what part of the sentence is underlined? What’s next to the underlined section? Does it ‘sound’ correct? Are there any errors that pop out at me?

Once you’ve read the stimulus, pause and ‘survey the landscape’ of the answer choices. Ask yourself:  How can I group these together? What do they have in common? It’s important to note that to split the answer choices, you don’t have to read every word. Instead, look at the beginning, middle, and end of each choice for decision points. For instance, if you see different verb tenses or different pronouns, this will show you potential errors in the sentence.

Here we can see that the answer choices are split between singular and plural verbs in the present perfect tense. When this error occurs, the first place you should look is to the subject that’s being described. In this case, the subject is ‘rock samples’. Rock samples aren’t a singular cohesive group:  they’re a collection of separate samples, which makes the subject plural. Therefore, the verb must be plural. Answer choices A & B can be eliminated.

Rock samples taken from the remains of an asteroid about twice the size of the 6-mile-wide asteroid that eradicated the dinosaurs has been dated to be 3.47 billion years old and thus is evidence of the earliest known asteroid impact on Earth.

a) has been dated to be 3.47 billion years old and thus is

b) has been dated at 3.47 billion years old and thus is

c) have been dated to be 3.47 billion years old and thus are

d) have been dated as being 3.47 billion years old and thus

e) have been dated at 3.47 billion years old and thus are

After you’ve split the answer choices once, read the remaining answer choices carefully. Ask yourself:  what’s different between the remaining answer choices? For one, D doesn’t have a verb at the end of it. If you eliminate the modifying phrases in the stimulus, you’re left with:  “Rock samples [...] evidence of the earliest known asteroid impact on Earth.” Answer choice D is incorrect because it doesn’t provide the sentence with a verb.

Rock samples taken from the remains of an asteroid about twice the size of the 6-mile-wide asteroid that eradicated the dinosaurs has been dated to be 3.47 billion years old and thus is evidence of the earliest known asteroid impact on Earth.

a) has been dated to be 3.47 billion years old and thus is

b) has been dated at 3.47 billion years old and thus is

c) have been dated to be 3.47 billion years old and thus are

d) have been dated as being 3.47 billion years old and thus

e) have been dated at 3.47 billion years old and thus are

We’ve narrowed it down to two. Again, ask yourself:  what’s different between the remaining answer choices? Looking at both C and E, you’ll see that the idiom ‘dated’ is used in two different forms. Do you think something can be ‘dated to be’ a certain age or ‘dated at’ a certain age? Don’t overthink it, use logic:  the correct answer is ‘dated at’. Rock samples aren’t a date; they ‘be’ rock samples, not a ‘date’. Answer choice E is correct.

***

In middle school everyone thought it was a great idea to begin their essays with, ‘Merriam Webster defines my topic as…’ I’m going to break one of my rules and use that same trope:  the Merriam Webster dictionary defines grammar as “the whole system and structure of a language”. I think that’s a powerful point to end on. Just as grammar can’t be reduced to comma rules and prepositional phrases, SC is a test of critical thinking skills.

Remember, you can reason your way through both GMAT practice questions and test questions a lot easier than you can ‘grammar’ your way through it. If you use the routine and strategies discussed above, you’ll have more than enough resources to excel at SC. Of course, on easier questions you might not need to follow the entire routine - just like Quant, all that matters is that you select the correct answer. Feel free to adjust your strategy accordingly.