Updated 2026-08-23intermediate

TOEFL Reading Practice #016 — The Small-World Phenomenon

Free TOEFL Reading practice: The Small-World Phenomenon. 11 questions with a full passage and answer key.

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How to use this practice: Read the passage once without a dictionary, then answer the questions on your own. Tap “Answer” under each question to reveal just the correct letter — no explanations, so you can keep testing yourself.
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Passage

Read the full passage. Bracketed letters like [A] mark the four positions for the insert-text question.

The Small-World Phenomenon

¶1 Two strangers who meet by chance can find they know someone in common. Neither one expected any connection at all. This pattern has a name: the small-world phenomenon. It happens when any two people are linked through only a short chain of acquaintances. It shows up in ordinary conversation, whenever two people discover a friend in common. In 1929, long before anyone tested the idea, the Hungarian writer Frigyes Karinthy made a guess. He suggested that any two people on Earth might be connected through a chain of only about five acquaintances. At the time, the claim sounded entertaining, not something anyone could actually measure.

¶2 The striking part of the small-world phenomenon is that these chains are supposed to stay short. That is true even though the world holds an enormous number of people. If each person knows a few hundred others, the number of possible paths between any two strangers multiplies almost without limit, yet the actual shortest chain rarely runs longer than half a dozen steps. That property is difficult to confirm. No single person can see the whole map of who knows whom across an entire country, let alone the planet. Testing Karinthy's claim would mean tracing real chains of acquaintance through thousands of people at once. For decades, no one had a practical way to do that.

¶3 Researchers eventually found two different ways to test the claim. In 1967, the psychologist Stanley Milgram mailed folders to volunteers in Nebraska. He asked each volunteer to send it toward a specific stockbroker in Boston. The rule was simple: give it only to someone you know personally. [A] Each volunteer added their name to the folder before passing it along, so the finished chains could be counted step by step. [B] Many folders never reached their target, but the ones that did had passed through about five and a half people on average. [C] Decades later, researchers tested the same idea with a different kind of record: the network of friendships on Facebook. [D] That network connects hundreds of millions of accounts to one another. Measuring the shortest online path between random users produced an average distance of about four and a half steps. Two very different methods, one built from paper and mailboxes and the other from computer records, had arrived at nearly the same number.

¶4 The consistency of that result changed how scientists think about large networks. It suggested that short chains are not a special feature of human friendship, but a general property of many kinds of networks. Examples include power grids, computer networks, and the paths along which diseases spread through a population. In this way, a simple guess made by a Hungarian writer in 1929 grew into a tool that shapes fields well beyond sociology. It now helps engineers design efficient transportation systems and helps researchers predict how quickly information, or misinformation, can travel through an entire population.

  • acquaintance: a person you know but who is not a close friend
  • stockbroker: a person whose job is to buy and sell stocks for other people
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Questions

11 questions — every TOEFL Reading question type, in test order.

Q1 · Vocabulary
The word enormous in paragraph 2 ("That is true even though the world holds an enormous number of people.") is closest in meaning to
  1. A. tiny
  2. B. huge
  3. C. unknown
  4. D. connected
Answer
Correct: B
Q2 · Reference
The word It in paragraph 1 ("It shows up in ordinary conversation, whenever two people discover a friend in common.") refers to
  1. A. a chance meeting between two strangers
  2. B. a short chain of acquaintances
  3. C. ordinary conversation
  4. D. the small-world phenomenon
Answer
Correct: D
Q3 · Essential Term
Based on the information in the passage, the term small-world phenomenon can best be explained as
  1. A. the finding that two strangers are usually connected through only a short chain of people who know each other, even though the world holds an enormous number of people
  2. B. a method scientists use to count how many friends a person has on a social media account
  3. C. any group of close friends who all happen to already know one another
  4. D. the exact number of acquaintances — five — that separates any two people on Earth, as Karinthy first guessed
Answer
Correct: A
Q4 · Factual Information
According to paragraph 1, what did Frigyes Karinthy suggest in 1929?
  1. A. That the small-world phenomenon could easily be measured using mailed folders
  2. B. That most strangers who meet by chance already know each other personally
  3. C. That any two people on Earth might be connected through a chain of only about five acquaintances
  4. D. That chains of acquaintance grow longer as the number of people in the world grows
Answer
Correct: C
Q5 · Negative Fact
According to paragraph 3, all of the following are true EXCEPT
  1. A. Stanley Milgram mailed folders to volunteers in Nebraska in 1967
  2. B. Volunteers were told to give the folder only to someone they knew personally
  3. C. Researchers later measured the shortest path between users of Facebook's friendship network
  4. D. Every folder mailed by Milgram eventually reached the stockbroker in Boston
Answer
Correct: D
Q6 · Sentence Simplification
Which of the sentences below best expresses the essential information in the highlighted sentence in paragraph 2? Incorrect choices change the meaning in important ways or leave out essential information.

Highlighted: "If each person knows a few hundred others, the number of possible paths between any two strangers multiplies almost without limit, yet the actual shortest chain rarely runs longer than half a dozen steps."
  1. A. Even though the number of possible paths between two strangers grows almost without limit as each person's acquaintances multiply, the actual shortest connecting chain stays remarkably short, rarely more than about six steps.
  2. B. Because the number of possible paths between two strangers is limited, the shortest chain connecting them is usually about six steps.
  3. C. The number of possible paths between two strangers grows without limit, so no one has ever found the shortest chain connecting them.
  4. D. Only when each person knows several hundred others does the shortest chain between two strangers ever reach six steps.
Answer
Correct: A
Q7 · Inference
Based on the information in paragraphs 2 and 3, what can be inferred about why Stanley Milgram's 1967 experiment was an important test of Karinthy's claim?
  1. A. Because Milgram was the first person to propose that two strangers might be connected through a short chain of acquaintances
  2. B. Because his experiment proved that chains of acquaintance could never be traced using computer databases
  3. C. Because no one before him had found a practical way to trace real chains of acquaintance through a large population, and his experiment did exactly that
  4. D. Because he was able to record exactly how each volunteer decided which acquaintance to send the folder to
Answer
Correct: C
Q8 · Rhetorical Purpose
The author mentions the later study that used Facebook's friendship network in order to
  1. A. criticize Milgram's experiment for using too few volunteers
  2. B. provide a modern, independent test of the same idea using a completely different method
  3. C. explain how the Facebook website was originally created
  4. D. argue that online friendships are stronger than real-world acquaintances
Answer
Correct: B
Q9 · Paragraph Relation
How does paragraph 3 relate to paragraph 2?
  1. A. It shows that the difficulty described in paragraph 2 made the small-world phenomenon impossible to test
  2. B. It describes two specific methods that address the difficulty of testing the claim described in paragraph 2
  3. C. It introduces a different phenomenon that has nothing to do with the property discussed in paragraph 2
  4. D. It contradicts the claim about short chains that paragraph 2 describes
Answer
Correct: B
Q10 · Insert Text
Look at the four squares [■] in paragraph 3 that indicate where the following sentence could be added.

It was a surprisingly short number for a country as large as the United States.

Where would the sentence best fit?
  1. A. Square A
  2. B. Square B
  3. C. Square C
  4. D. Square D
Answer
Correct: C
Q11 · Prose Summary Select THREE · 2 pts
Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

The small-world phenomenon is the surprising finding that two strangers are usually connected through only a short chain of acquaintances, and two very different research methods have confirmed that this short-chain pattern is real.

  1. A. The idea that two strangers might be connected through a short chain of acquaintances was first suggested by the Hungarian writer Frigyes Karinthy in 1929.
  2. B. No single person can see the whole map of who knows whom across an entire country, let alone the planet.
  3. C. Many of the folders mailed in Stanley Milgram's 1967 experiment never reached the stockbroker in Boston.
  4. D. Milgram's mail experiment and a later study of Facebook's friendship network both found an average chain length of only about four or five steps.
  5. E. Understanding why networks have such short paths now shapes fields such as transportation design and the study of how information or diseases spread.
  6. F. Facebook was created specifically to test the small-world phenomenon.
Answer
Correct: A, D, E