3 Reasons You Need to Use Your Scratch Pad for Sentence Correction

It is incredibly common how many GMAT students have ZERO strategy when it comes to Sentence Correction. Most students just read (A) and try to see if something “sounds weird,” then continue on to (B), (C), (D), and (E), often reading and re-reading each of the 5 choices until they choose what “sounds right” to them, or which one they like the “best” out of the 5. This is NOT a time-efficient or accurate way of doing Sentence Correction! Let’s look at three “home truths” we need to digest in order to move our grammar skills from “okay” to “foolproof!”

High-scorers do not do SC on “feel.” It’s great if you read a sentence and you can sense something is “wrong” or “off” about it, but if you cannot pinpoint WHAT is wrong and WHY it is wrong, then you don’t know Sentence Correction as well as you think. Without writing down a GMAT reason, how do you know that the reason you are elimination Choice (A) is because of a GMAT error and not simply your own gut instinct?

If you don’t record your impressions, you can learn nothing from them. Let’s say you’re taking a full-length practice test. There are 41 questions in the Verbal section. That’s a LOT of questions!

Let’s say you missed Question #5 and it was a Sentence Correction. You go back to the problem a 2-3 hours after completing your practice test to review all your incorrect questions. You have some fuzzy memories of the specific question, but it’s been a few hours, and you did 36 questions after it, so of course you won’t recall it too distinctly.

You look at your scratch pad for this question and it looks like this:

A
B
C
D
E

What does this tell you about what you were thinking in your mind as you did the problem? Absolutely nothing. 😦

Therefore, you don’t really have anywhere to go. You can see you chose (D), but you don’t know why. How are you supposed to learn from the question? You read the official explanation, and some additional explanations from GMATPrep or Beat the GMAT, but they don’t tell you what YOU were thinking when you were working through the problem. Let’s say the correct answer was (E). You have no idea why you crossed it off. There is no record. So, how can you improve?

We don’t have Predictions for SC.  Sometimes students try to use symbols for their process of elimination. Symbols such as happy or sad faces and plus or minus signs are great tools to use for Reading Comprehension and Critical Reasoning answer choices, because we are comparing those answer choices to a pre-conceived idea, a prediction for what we think the correct answer will look like.

But, sadly, in SC we have no idea what the correct sentence is going to look like! Maybe it will look like (A). Maybe it will look completely different from (A).

Let’s say your scratch pad for our hypothetical Question #5 looked like this:

A ?
B –
C –
D +
E ?

This gives us a tiny bit more information about what we were thinking when we looked at each choice, but still not nearly enough. We aren’t thinking like the GMAT test-makers yet, because we aren’t “speaking” their language. They write answer choices to include these specific errors, so we need to be able to point out and name those specific errors. It’s the only way to achieve true Sentence Correction mastery. We have to think like the test-makers!

Now let’s say we DID try to apply our content knowledge of tested grammar/meaning errors to Question #5. Our scratch pad could reveal something like this:

A S/V
B Para
C Mod
D Wordy?
E Para?

Suddenly, we have a LOT of great questions to ask ourselves:

• In (A), (B), and (C) was there really a Subject-Verb, Parallelism, and Modification issue? Did I recognize these errors correctly? What markers told me this error was present? Or did I miss the “real” error, and simply got lucky in my elimination?
• In (D), was there a grammar or meaning error I could not spot that made this choice incorrect? If so, what was it, and why couldn’t I spot it? What were the markers that indicated it was being tested? If there was no grammar or meaning error, was the only issue with this sentence the wordiness, or was another “style” error present?
• In (E), the correct choice, why did I invent a Parallelism error when no Parallelism error was present? What were the markers that made me think it was testing this concept, and WHY was the Parallelism actually okay? What do I need to remember about Parallelism so I can be more careful and not invent future Parallelism errors?

You will not be able to do this type of self-analysis without the knowledge of what your thought process was as you were attempting the problem!

Just because you speak English, read English, and feel like you generally understand English, don’t be fooled into thinking you don’t need to use strategy for GMAT Sentence Correction! It’s incredibly important for your growth and betterment, and my mission is to help you do it!

How to Move your GMAT Verbal Score 40+ Points…In 2 Weeks!

Have you already gone through the Verbal questions in GMAC’s Official Guide, reviewed the MGMAT Sentence Correction book, and covered the Powerscore CR book? Feeling a GMAT Verbal plateau and not sure what to do next? Here’s some solid tips to move your GMAT Verbal score an extra 40 points in just under 2 weeks!

Beef up the grammar skills. You can ignore most of the challenging vocabulary on sentence corrections as long as you identify what part of speech each word is, and how it functions within the sentence. To do this, you’ll need to spend some time with a solid English grammar review book. I recommend pairing a heavy-duty review book, like the Oxford Guide or those published by McGraw-Hill or Longman, with a “fun” book like Writer’s Express or English Grammar for Dummies.

Read and listen to high-quality English publications. My recommendations include The New Yorker, the Atlantic Monthly, the New York Times, the Wall Street Journal, or any scholarly journal that you find interesting. Listen to NPR or audio books of English-language classics. Set a regular schedule for your reading and stick to it. Even twenty minutes a day will help you conquer Reading Comprehension.

Seek out Advanced CR for harder vocab words. Once you’ve practiced identifying the conclusion, evidence, and assumptions and are confident with the Critical Reasoning question types on the GMAT, consider buying an LSAT practice guide like the LSAT LR Bible. The LSAT has significantly more challenging CR questions and the format is the same as those found on the GMAT. Don’t neglect your GMAT practice, but if you can master the LSAT CR, then the GMAT questions will start to feel easier.

Go more slowly with Word Problems. Practice translating these questions from English keywords to Math equations. Be patient at first – these questions may be especially frustrating vocab-wise. Luckily, the common phrases such as “less than,” “is the same as,” and “product of” are easily memorized.

CRITICAL REASONING TIPS

Identify the Conclusion, Evidence & Assumption(s). This should be your first step for all of the Critical Reasoning question types. The conclusion and the evidence will be explicitly stated in the passage, while the assumptions will require you to sit and consider the author’s point of view. What needs to be true in order for the conclusion to be correct based on the given evidence?

Find the purpose of each sentence. Sometimes CR questions will ask what the function is of a part of the argument. You may see questions that ask “which role” a sentence plays. Try to place it into one category: conclusion ,or evidence? If the sentence was removed from the paragraph, what would be lacking?

Know the overall flow. Arguments have a tendency to follow one of two shapes: a triangle or an inverted triangle. Does the author start by making a specific conclusion and then provide more general evidence, or does he begin with observations and then get to a thesis? Use variables to describe the structure. “Y leads to X which leads to Z” is different from “Y turns into Z unless Y is prevented.” Be on the lookout for “If X, then Y” relationship.

Paraphrase the argument. Dumb down the complexity of the argument as you read, as if you were explaining it to a child. You may want to write down a few short notes to help you. The idea is to ignore the petty details and see through to the author’s main point and to the evidence he provides to support his point.

Choose a verb. Questions about argument structure often ask about the “methods” an author uses. You already know the flow of the overall argument, now give it an overall purpose and label as an infinitive verb. Common verbs:

to explain
to dismiss
to theorize
to strengthen
to demonstrate
to revise
to assert
to suggest
to interpret
to reconcile
to challenge
to predict

Look for transitions. Transition words and phrases are like signposts pointing your way through the logic of the argument. They tell you what is coming next. “Specifically…” means a more detailed example will follow. “Thus,” means a summation is to be expected. “While this may be true…” is a phrase that shows a concession is about to be made. Keep a study sheet of transition words and divide them into categories: Examples, Adding, Contrasting, Emphasis, Resulting In, etc. It’s an ongoing process to familiarize yourself with these, but a worthwhile one.

Determine what is missing for Complete the Passage Questions. What does the blank represent? Often it will be either a restatement of the conclusion, or another supporting piece of evidence, but it could also be an action advocating by the author, or an example of the author’s argument applied to the real world.

Make a prediction (and write it down)! This is the most important strategy for CR. You’ve got to trust that you understand the argument enough to know what should be the correct answer. Don’t worry about making it perfect – just get something down on paper! If you think of your prediction but don’t write it down, you risk forgetting it or twisting it to fit the answer choices.

Eliminate out-of-scope answers. While the correct answer may not perfectly match your prediction, the simple fact that you took the time to think critically while you came up with a prediction will help you understand the author’s focus and the flow of his argument. Eliminate answer choices that would NOT follow the gist of the paragraph. Especially look for those that are outside the scope of the author’s focus, a favorite CR wrong answer type!

Try the Negation Technique. An assumption is something that needs to be true and is required in order for the Evidence to lead to the Conclusion. If we negate the answer choices then the correct choice will weaken the argument the most. This is an excellent strategy to try for Assumption questions.

Questions? Feel free to reach out at gmatrockstar[at]gmail.com! I look forward to helping you on your GMAT journey!

Sentence Fragments and Run-Ons: Pacing Drill

Ready to try a quick 5-question pacing drill for problems involving Sentence Fragments and Run-On Sentences?

Set your timer for 12.5 minutes if you’re still new to Sentence Correction, 10 minutes if you’ve done a good amount of review and feel confident in your knowledge of Sentence Fragment and Run-On Sentences,  7.5 minutes if you want to give yourself a challenge, ot 5 minutes if you’re a Sentence Correction rock star!

Answer ALL 5 of the following questions, then read through the explanations.

Question #1

In the late nineteenth century, the idea that women held an intrinsic right to vote as American citizens was foreign to most males; in our modern time, however, most males accept it as a foregone conclusion.

(A) to most males; in our modern time, however, most males accept it as a foregone conclusion.

(B) to most males, in our modern time, henceforth, most males accept it as a foregone conclusion.

(C) to most males; in our modern time, although, most males are concluding of it as foregone.

(D) for many males; in our modern time, though, most males accepted it as a foregone conclusion.

(E) for many males; in our modern time, however, most males will accept it as a foregone conclusion.
Question #1 Solution:

The semi-colon and the contrast transition “however” correctly establish the meaning of this sentence, which the present-tense “accept” is appropriate.

Choice (B) creates a run-on sentence by replacing the semicolon with a comma. Without a connecting conjunction—and, or, but, etc.—two independent clauses must be joined by a semicolon or written as two separate sentences in order to avoid creating a comma splice or a run-on. In addition the word “henceforth” not imply the proper contrasting meaning.

Choice (C) uses the very awkward construction: “are concluding of it,” and “although,” though used to indicate contrast, is used awkwardly here. Choice (D) contains an error in tense. The sentence progresses from the past to the present, so the verb in the second clause should be the present-tense “accept.” Choice (E) incorrectly uses the future tense “will accent.” The phrase “modern time” indicates the action takes place in the present. The correct answer is (A).
Question #2

That his presentation on compound interest initiatives was criticized harshly by the members of the bank’s board who examined his proposal with relative indifference came as a shock to the low-level executive.

(A) That his presentation on compound interest initiatives was criticized harshly by the members of the bank’s board who examined his proposal with relative indifference came as a shock to the low-level executive.

(B) The low-level executive was shocked that his presented proposal on compound interest initiatives was criticized harshly by the members of the bank’s board who examined it relatively indifferently.

(C) The fact that his presentation on compound interest initiations was criticized harshly by the members of the bank’s board, which had examined it with relative indifference, came as a shock to the low-level executive.

(D) Shocked that his presentation on compound interest initiatives was criticized harshly, the members of the bank’s board examined the proposal by the low-level executive with relative indifference.

(E) Examining it with relative indifference, the bank’s board examined the proposal on compound interest initiatives by the low-level executive with harsh criticism, shocking him.

Question #2 Solution:

There is nothing incorrect with the existing sentence in (A). Don’t confuse complex or unusual sentence structure with grammatical error. “That” is correctly used. Choice (C) may have been tempting, but it’s less concise and contains several drawn-out clauses. Choice (D) contains a modification error. As written, it implies the “board” was “shocked” but it’s the “low-level executive” who is shocked. (B) and (E) are wordy and awkward. In (B), there should also be a comma before the word “who” since it creates a new clause. In (E), it is also unclear what “it” refers to. We cannot introduce a pronoun without a clear, logical antecedent. The correct answer is (A).

Question #3

The question-at-hand brought up and then debated by the local housing council which was whether or not to require a minimum lot size for any home built after 1978.

(A) which was whether or not to require a minimum lot size for any home built

(B) was whether or not to require a minimum lot size for any house they build

(C) was whether or not to require a minimum lot size for any house built

(D) was the requirement of whether or not a minimum lot size was needed for any house

(E) whether or not to require a minimum lot size for any house built

Question #3 Solution:

The original sentence is a fragment; even though it has multiple verbs and verb forms it does not express a clear thought. (E) is also a fragment. We must eliminate “which” to help create an independent clause. This is done by choice (C). Choice (B) removes “which,” but it has a pronoun, “they” with no clear antecedent. If you chose (D), this option is unnecessarily wordy. A grammatically correct, less wordy option (such as (C)), will always be preferable to an option such as (D). The correct answer is (C).

Question #4

The concept of a wireless radio in every room of one’s home was viewed as beyond luxurious at one point, at first as a result of the fact that early wireless sets were extremely pricey and, in more current times, because they seemed nonessential.

(A) at first as a result of the fact that early wireless sets were extremely pricey and, in more current times, because

(B) at first this was because early wireless sets were extremely pricey, and in more current times due to the fact

(C) at first because early wireless sets were extremely pricey and in more current times because

(D) at first being extremely pricey, in more current times

(E) at first because they were extremely pricey, but then in more current times because

Question #4 Solution:

Remember on the GMAT that not all lengthy answer choices will be incorrect, but always check for a more concise version. (C) is the most concise version of the sentence that does not introduce additional errors. (B) and (D) create run-ons. (B) and (D) do this by making the second clause independent. Both “at first this was because…” and “at first because…” could stand on their own as complete sentences. Independent clauses cannot be separated by commas. They should be separated by semicolons. (E) contains an error in meaning. The word “but” in (E) creates a contrast between the clauses, but both clauses support the same idea (radios in every room were seem as a luxury), so not contrast is needed. The correct answer is (C).

Question #5

Before scientists learned how to make a synthetic growth hormone, removing it painstakingly in small amounts from the pituitary glands of human cadavers.

(A) scientists learned how to make a synthetic growth hormone, removing it painstakingly

(B) scientists had learned about making a synthetic growth hormone, they had to remove it painstakingly

(C) scientists learned how to synthesize the growth hormone, it had to be painstakingly removed

(D) learning how to make a synthetic growth hormone, scientists had to remove it painstakingly

(E) learning how to synthesize the growth hormone, it had to be painstakingly removed by scientists

Question #5 Solution:

(A) is a sentence fragment. What’s the subject? What’s the predicate verb? This sentence is a mess. We don’t know who is doing the action. Logically it should be the scientists, but “scientists” is in a dependent clause and not independent. This sentence has tried to join two dependent clauses together to make a sentence.  (C) is the correct answer because it gives us a subject (“it”) and creates a stand-alone independent clause.

Learnist: 7 Ways to Make Studying for the GMAT Fun!

(No, really!) Here’s how to dance, snack, and gamify your way to a 700+ GMAT score.

Tip #1 – Use Music As Motivation (Exhibit A: The USC Marshall School of Buiness doing the “Harlem Shake”)

In this video the MBA candidates of the Class of 2013 and Class of 2014 at the University of Southern California Marshall School of Business decided to do the Harlem Shake.

And while you may not want to waste a precious study-hour making your own Harlem Shake dance-video with your GMAT study group (but by all means, please feel free to do so!), you CAN and SHOULD use music as motivation while you study for the GMAT.

If you’re someone who needs to have background noise as you study, assign a genre of music to each GMAT question-type. Planning to do 20 minutes of Sentence Correction? It’s Britney Spears and Katy Perry! Moving on to Data Sufficiency? It’s Macklemore-time.

Check out Tips #2-7 on Learnist to learn more ways to make studying for the GMAT fun!

Learnist Board of the Week: Destroy GMAT Reading Comp (once and for all)

Check out this new Learnboard with a step by step guide to conquering RC once and for all!

Step 1 — To start, here’s the mandatory books you’ll need to get:

  • GMAT Official Guide – 13th edition
  • GMAT Official Guide – Verbal review, 2nd edition

You’ll want to know the RC questions in this book backwards, forwards, and upside down.

Other books with lots of passages to practice:

  • Veritas Prep – Reading Comprehension Guide
  • Manhattan GMAT – RC Strategy Guide
  • Artistotle Prep – RC Grail

Step 2 — Read The Economist, or other high-quality publications!

The Economist is a weekly newspaper focusing on international politics and business news. Not only is its subject-matter right up GMAT’s alley, but its written in a more advanced vernacular than your average newspaper — a level matched by the GMAT RC.

As you read these articles, do the following:

  • Circle the topic
  • Underline any transition words
  • Write down the purpose of each paragraph
  • Write down the author’s point of view in your own words
  • Write down the Main Idea in your own words

Do all of this to build your RC skills — ALWAYS read with a pen in your hand, and always ask the million dollar question, “Why is the author saying this?”

Fun fact: You can use your Delta Skymiles for a free subscription. 3,200 miles gives you 51 issues!

For Steps 3 through 7, check out How to Destory GMAT Reading Comp (once and for all)!

 

Grammar Guide: the usage of “those”

Confused about how “those” works on the SAT, ACT, GRE, or GMAT? Let’s take a look at a question from Manhattan GMAT that uses this word!

Salt deposits and moisture threaten to destroy the Mohenjo-Daro excavation in Pakistan, the site of an ancient civilization that flourished at the same time as the civilizations in the Nile delta and the river valleys of Tigris and Euphrates.

A) that flourished at the same time as the civilizations
B) that had flourished at the same time as had the civilizations
C) that flourished at the same time those had
D) flourishing at the same time as those did
E) flourishing at the same time as those were

In general, “those” is the plural of “that.” It’s in a group called “determiners” along with “this”, “that”, “these”, “those,” “here” and there that are technically pronouns but often function more like adjectives.

For C, D, and E, “those” is meant to mean something like “the ones” and could be used as a pronoun to replace a plural antecedent if there was one in the sentence, and if the construction was parallel.

The correct answer is (A).

Learnist: GMAT “Logical Structure” Reading Questions

Questions that ask about the “function” of a detail, sentence or paragraph is a Logical Structure question. These frequently appear on the GMAT — always look for the logical keywords that tell you where the author is taking the discussion.

Authors organize their ideas in paragraphs, and each paragraph has a mini-purpose. Why, otherwise, would the author write it? Try to get a sense of the function of EACH paragraph as you read by looking for the keywords. Put the “function” in your own words and write it down!

Since keywords and phrases are ALL you have to go on to extrapolate the structure of the passage and the author’s intentions, practice pulling out the key phrases in this passage. Then scroll down, comparing them to those the author identified.

 This blog is for GRE passages, but they are the same in terms of form and content to the GMAT. Notice the list of “Function” verbs here. Copy them down and try to “assign” an infinitive verb to each paragraph. What is author DOING with each paragraph?

Just like every paragraph has a function, each sentence within each paragraph has a function. Start with the overall function of the paragraph, then ask: how does this detail relate to the paragraph’s overall function? Is it aiding the main idea? Qualifying it? Making a concession?

10 Tips for Non-Native Speakers on the GMAT

Even if English isn’t your first language, you can still achieve an excellent score on the GMAT Verbal section. Here are a few tips to get you started!

1. Build your grammar skills first. You can ignore most of the challenging vocabulary on sentence corrections as long as you identify what part of speech each word is, and how it functions within the sentence. To do this, you’ll need to spend some time with a solid English grammar review book. I recommend pairing a heavy-duty review book, like the Oxford Guide or those published by McGraw-Hill or Longman, with a “fun” book like Writer’s Express or English Grammar for Dummies. Start identifying the subject and the verb of every sentence correction, as well as any dependent clauses. Strategy alone won’t get you the Verbal score you want. Start your Verbal studying with grammar.

2. Keep a vocabulary journal. Write down any words you don’t know as you encounter them. You’ll start to notice that certain words appear over and over again. Make flashcards for the ones that have tricky definitions or mean the opposite of what you’d expect. (For example, the word “noisome” does not mean “noisy.” It means having an offensive odor or bad smell.)

3. Apply your idioms. Yes, you absolutely need to memorize English idioms, but don’t just be an idiom robot. Start applying them in your everyday speech, emails, and English compositions. The more you can incorporate them into your English writing, the more confident you’ll become.

4. Think like a thesaurus. It is much easier to memorize synonyms for words than their full definitions. Start grouping words together mentally (and on paper) according to their meaning. For example, words like “pusillanimous,” “poltroonish,” and “timorous” would go on the “shy” list.

5. Read and listen to high-quality English publications. My recommendations include The New Yorker, the Atlantic Monthly, the New York Times, the Wall Street Journal, or any scholarly journal that you find interesting. Listen to NPR or audio books of English-language classics. Set a regular schedule for your reading and stick to it. Even twenty minutes a day will help you conquer Reading Comprehension.

6. Create a study group. Whether in real life or online, connect with other native and non-native speakers who are prepping for the GMAT. Check out your local library and schools and set up a weekly coffee shop meet-up to discuss your progress. Create a Yahoo group. Join Grockit (of course!). This will not only help you stick to your goals, but also help you learn about new resources from other non-native speakers and gain insight from those who have more advanced English skills.

7. Consider the difference between British and American English. Many English-language schools outside of the United States focus on British English, while the GMAT is an American-administered test. There are subtle differences in word choice and spelling between the two. While British spellings are officially acceptable in the AWA section, I would suggest familiarizing yourself with their American counterparts and using them to be safe.

8. Challenge yourself with CR. Aiming for a 700+ score? Once you’ve practiced identifying the conclusion, evidence, and assumptions and are confident with the Critical Reasoning question types on the GMAT, consider buying an LSAT practice guide like the LSAT LR Bible. The LSAT has significantly more challenging CR questions and the format is the same as those found on the GMAT. Don’t neglect your GMAT practice, but if you can master the LSAT CR, then the GMAT questions will start to feel easier.

9. Spend more time on Word Problems. Though Data Sufficiency certainly requires a significant amount of Quantitative study, remember to save extra time for Word Problems. Practice translating these questions from English keywords to Math equations. Be patient at first – these questions may be especially frustrating. Luckily, the common phrases such as “less than,” “is the same as,” and “product of” are easily memorized.

10. Look at your situation as an advantage! Many native speakers are confused by answer choices that include have slang, contain popular (though incorrect) grammatical phrases, or just “sound right.” Non-native speakers learn the exact same question types and strategies as native speakers, but can apply them without any prejudice. It really is an advantage!

How Drawing a Picture Can Help you Get More GMAT CR Correct!

Take a look at this Critical Reasoning question from 1000 CR:

Archaeologists seeking the location of a legendary siege and destruction of a city are excavating in several possible places, including a middle and a lower layer of a large mound. The bottom of the middle layer contains some pieces of pottery of type 3, known to be from a later period than the time of the destruction of the city, but the lower layer does not.

The force of the evidence cited above is most seriously weakened if which of the following is true?

(A) Gerbils, small animals long native to the area, dig large burrows into which objects can fall when the burrows collapse.
(B) Pottery of types 1 and 2, found in the lower level, was used in the cities from which, according to the legend, the besieging forces came.
(C) Several pieces of stone from a lower-layer wall have been found incorporated into the remains of a building in the middle layer.
(D) Both the middle and the lower layer show evidence of large-scale destruction of habitations by fire.
(E) Bronze ax heads of a type used at the time of the siege were found in the lower level of excavation.

This one is interesting since we are not provided with a conclusion, so we have to draw one based on the evidence.

Evidence: Bottom of middle layer contains pottery 3. Pottery 3 is made AFTER the destruction.

I’m going to draw a picture, because drawing is fun, and totally under-rated when it comes to GMAT Critical Reasoning. 🙂

We can infer that usually the deeper the level = the older the time period. Since as we move forward in time, we generally build up on things.

So, the city was probably destroyed around the lower layer, or in the middle layer but beneath where the pottery was found.

Question: What casts doubt on the Type 3 pottery in the middle layer/destruction of city inference?

Prediction: If the pottery was moved around — if the location doesn’t represent the time period accurately.

A – decent choice, shows pottery could’ve been moved
B – doesn’t comment on Type 3 pottery
C – this implies at some point the middle-layer people used the wall below them to build up — but doesn’t show that the pottery could have moved down or up
D – Fire is totally irrelevant
E – “at the time of the siege” is vague — and this doesn’t relate at all to the pottery evidence

The correct answer is (A).

GMAT CR: “Strengthen” Question of the Day!

A broken shard of glass found in the laboratory of the famed physicist Alhazen has a polished surface that separates out the green and blue spectrums of white light, a key characteristic of a dispersive prism, which separates white light into all its constituent spectral components. Scientific historians, based on this finding, are revising their histories in order to give Alhazen, the “father of modern optics,” credit for the discovery of the dispersive prism, which was thought to have been discovered many years later.

Which of the following, if true, most strongly supports the historians’ decision to revise the history of optics?

A. Dispersive prisms were the only type of prism that was theorized about in the scientific era in which Alhazen lived.

B. The piece of glass from which the shard broke, if unbroken, would have been just large enough to separate out the entire spectrum of white light into its spectral components.

C. The piece of glass was a combination of flint glass, which was known to have been used by Alhazen to craft lenses in his laboratory, and crown glass, another popular type of glass throughout history.

D. Dispersive prisms are the simplest and most common objects that are able to divide white light into its constituent spectral components.

E. Several glass objects that are known to have some properties of a dispersive prism have been found to be older than the glass piece in Alhazen’s laboratory.

Explanation:

Conclusion: Historians give A credit for prism.

Evidence: Glass found that has characteristic of prism.

Assumption: Glass not there by accident; glass definitely means A “discovered” prism.

Question: What STRENGTHENS?

Prediction: Anything that links this glass to the prism, removes coincidence.

A – Other prisms out of scope.
B – This connects the glass to the prism.
C – The type of glass is irrelevant.
D – This is just a fact about the prism.
E – This would weaken, since it makes the glass/prism link less strong.

The answer is (B).