TOEFL Reading Academic Passage: Teacher Resource Set 5 on “Mysterious Viking Sun stones.”
Mysterious Viking Sunstones
The Vikings, seafaring warriors from Scandinavia, are believed to have navigated their ships with remarkable precision across the North Atlantic during the medieval period (about 500–1500 C.E.). [A] One key to their navigational success may have been the use of so-called “sunstones,” as described in Icelandic sagas (medieval Icelandic texts). Some argue the sagas’ content is mythical, while others suggest these stones were real tools used by the Vikings, probably crystals such as Iceland spar. Iceland spar is a transparent variety of calcite that possesses unique optical properties. [B] It polarizes light by splitting light into two beams, creating a double image when the stone is held up to the sky. By rotating the crystal, the Vikings could determine the location of the sun in the sky on cloudy days, which would help them maintain their course. [C] However, evidence of actual sunstone use remains scarce. Archaeologists have yet to uncover these stones in the remains of Viking settlements or ships. But an Iceland spar sunstone was recovered from a ship that sank in 1592, suggesting that this navigational tool was indeed used for quite some time. [D] The theoretical use of sunstones remains a fascinating example of Viking ingenuity.
16. Why does debate continue about the sunstones mentioned in Icelandic sagas?
(A) The sagas describe other uses for sunstones.
(B) Archaeologists have not found any such stones when examining Viking sites.
(C) Research indicates that sunstones are not actually an effective navigation tool.
(D) Researchers suspect that sunstones were not easy to obtain in the medieval period.
17. In what way was Iceland spar useful to Vikings?
(A) It helped them predict when clouds would disappear.
(B) It was used as a tool to help maintain ships.
(C) It helped them figure out where the sun was when it could not be seen.
(D) It was used to improve seafarers’ vision.
18. Why does the author mention a ship that sank in 1592?
(A) To explain how Elizabethans refined a technology invented by Vikings
(B) To support the theory that Vikings used Iceland spar for navigation
(C) To give an example of a more modern navigational tool
(D) To provide information about archaeological methods
19. The word “ingenuity” in the passage is closest in meaning to
(A) Education
(B) Cleverness
(C) Luck
(D) Fame
20. There are four locations in the passage that indicate where the following sentence could be added:
This is all the more remarkable considering the lack of technology at the time.
Where would the sentence best fit?
(A) Option A
(B) Option B
(C) Option C
(D) Option D
Hi everyone! Today we’re going to take a friendly tour of the new TOEFL Reading academic passage questions, and we’ll use an ETS sample set to practice together.
The questions on the passage types are almost the same as in the 2025 Reading section. The main change is that there is no summary question now. Instead, you may see a main idea question, which some of you already know well from TOEFL Listening.
In Reading, the test checks whether you can:
Understand the main idea of a passage
Find and use details
Understand implied (unstated) information
See the author’s purpose (rhetorical purpose)
See how the passage is organized
Understand vocabulary in context
Choose the best place for a sentence insertion
Today’s passage, from Teacher Resource Set 5, is called In this lecture, we’ll go through each question step by step so you can clearly see how to read and how to choose the correct answer.
Before touching the questions, always get the big picture of the passage. Think about how it is organized. This is very helpful for main idea, inference, and rhetorical purpose questions. When you read, try to divide the passage into three or four big ideas. You can imagine a camera zooming in and out while you read.
First, the passage starts with a wide shot. It sets the scene by introducing the Vikings as very skilled North Atlantic navigators and hinting that mysterious “sunstones” from Icelandic sagas might be the secret to their success.
Second, the camera zooms in on today’s “main character”: Iceland spar. The passage asks, “What are these sunstones?” and answers that Iceland spar is a clear calcite crystal, so you can think “Iceland spar = a kind of stone.” Then it describes the stone’s special properties in detail. You can skim most minor technical details here because they are not always important for the main storyline.
Third, the camera zooms out a bit to show the relationship between the stone and the Vikings. We see the benefit through a cause–effect link: by rotating this crystal under the sky, navigators could find the position of the sun even on cloudy days, which helped them stay on course. In simple form: “Use crystal → find hidden sun → stay on course.”
Finally, the camera pulls back even farther to give the “moral of the story.” Using the stone for navigation seems plausible, but there is not much direct evidence, so the idea is interesting and possible, but not fully proven.
This is the first module, so we can expect medium difficulty. If you do well here, your second Academic passage in the next module might be longer and harder, which can really help you score high. So try to get all of these right.
The Academic passage starts at Question 16. This is the first question.
Question 16: Why does debate continue about the sunstones?
When you see a “why” question, think: “What reason does the passage give?” Don’t use outside knowledge; stay inside the passage.
In the text, the author talks about disagreement right after explaining how Iceland spar might have worked. The key ideas are:
The sagas mention sunstones, and Iceland spar seems like a good candidate.
But archaeologists haven’t found sunstones in Viking settlements or ships, and the author says that evidence of actual sunstone use remains scarce.
So the debate continues because there isn’t enough physical (archaeological) proof that Vikings really used these stones, even though the idea is very plausible.
Now let’s look at the options one by one:
(A) The sagas describe other uses for sunstones.
The passage never says the sagas describe other uses. This is not mentioned, so we reject it.(B) Archaeologists have not found any such stones when examining Viking sites.
This matches exactly what the passage says: no sunstones have been found in Viking settlements or ships, and evidence remains scarce. This is the reason the debate continues, so this is what we’re looking for.(C) Research indicates that sunstones are not actually an effective navigation tool.
This is the opposite of the passage. The passage explains how Iceland spar could help find the sun on cloudy days, making it a plausible navigation tool. So (C) is false.(D) Researchers suspect that sunstones were not easy to obtain in the medieval period.
The passage never mentions how easy or hard it was to obtain sunstones. No mention, so we reject it.
So the correct answer is (B).
Now, some of you might think, “Wait, didn’t the passage say one was found in a sunken ship from 1592, so (B) can’t be true?” That’s a great question, and it’s one of the most common traps ETS sets: the scope of the claim.
Let’s reread the key part carefully. The passage says, “Archaeologists have yet to uncover these stones in the remains of Viking settlements or ships.” “Have yet to uncover” means no sunstones have been found in Viking‑period remains. Then it continues, “But an Iceland spar sunstone was recovered from a ship that sank in 1592, suggesting that this navigational tool was indeed used for quite some time.”
Notice the difference in scope and time:
The passage doesn’t say the 1592 ship was a Viking ship. It just says “a ship.”
The Viking Age is roughly 500–1500, but 1592 is after that period, so that ship is very unlikely to be a Viking ship.
So both ideas can be true at the same time:
No sunstones have been found at Viking settlements or on Viking ships.
A sunstone was found on non‑Viking ship in 1592.
That’s why (B) is still correct: it talks about Viking sites, and the 1592 ship doesn’t contradict that.
Question 17: How was Iceland spar useful to Vikings?
When you see a “How was X useful?” question, think: “What specific function does the passage describe?” Don’t generalize; go back to the description.
In the text, the author explains how Iceland spar works right after introducing it as a possible sunstone. The key ideas are:
Iceland spar splits light into two beams and creates a double image.
By rotating the crystal while holding it up to the sky, the user can determine the location of the sun.
This works even on cloudy days, and that helps them maintain their course.
So Iceland spar was useful because it helped navigators find where the sun was when they couldn’t see it directly, allowing them to stay on course.
Now let’s look at the options one by one:
(A) It allowed them to determine the sun’s position on cloudy days.
This matches exactly what the passage says: using the crystal, they could find the sun’s location even when it wasn’t visible, which helped navigation. This is what we’re looking for.(B) It helped them see the seafloor beneath their ships.
The passage never mentions anything about seeing the seafloor. Not mentioned → reject.(C) It enabled them to predict changes in the weather.
The crystal is used to locate the sun, not to forecast weather. This is not in the passage → reject.(D) It allowed them to measure the distance they had traveled.
There is nothing about calculating distance or speed. Again, not mentioned → reject.
So the correct answer is (A).
Question 18: Why mention the ship that sank in 1592?
When you see a “Why does the author mention X?” question, think: “What role does this example play in the argument?”
In the passage, the author first says that:
Evidence of actual sunstone use is scarce.
Archaeologists haven’t found these stones in Viking settlements or ships.
Then the passage says that an Iceland spar sunstone was recovered from a ship that sank in 1592. The key idea is:
This find shows that Iceland spar was really used on a ship for navigation, at least in a later period.
It doesn’t prove Viking use, but it supports the idea that this type of crystal was a genuine navigational tool.
So the shipwreck is mentioned to provide supporting evidence, not to prove the theory completely.
Now let’s look at the options one by one:
(A) To prove that Vikings definitely used sunstones for navigation.
(B) To give an example of a ship that relied on other navigational methods.
(C) To provide evidence that sunstones were actually used as navigational tools.
(D) To show that interest in sunstones began only in the late sixteenth century.
(A) To prove that Vikings definitely used sunstones for navigation.
Too strong. The passage never says “prove” or “definitely”; it only suggests and supports. Reject.(B) To give an example of a ship that relied on other navigational methods.
The ship is mentioned exactly because it had an Iceland spar crystal, not because it used other methods. Opposite → reject.(C) To provide evidence that sunstones were actually used as navigational tools.
This matches the passage: the 1592 shipwreck shows that Iceland spar was used in real navigation, which supports the idea that such stones could have been used more broadly. This is what we want.(D) To show that interest in sunstones began only in the late sixteenth century.
The passage never claims this. It connects the stone to much earlier Viking sagas, so interest clearly existed earlier. Reject.
So the correct answer is (C).
Question 19: What is the meaning of “ingenuity” as used in the passage?
For vocabulary-in-context questions, don’t jump to a dictionary meaning first. Ask: “What idea does this word express in this sentence?”
The passage uses a phrase like “a fascinating example of Viking ingenuity” after describing how they may have used a crystal to find the hidden sun and navigate without modern tools. The key idea is:
Vikings solved a difficult problem (navigation across the North Atlantic)
using a very clever, inventive method (sunstones/Iceland spar).
So here, “ingenuity” means cleverness or inventiveness in solving a problem.
Now let’s look at the options one by one:
(A) Strength
Strength is physical power. The passage focuses on a smart method, not physical power. Reject.(B) Cleverness
This fits perfectly: they found a clever solution to a hard navigation problem. This matches the context.(C) Tradition
Tradition means long‑standing customs or habits. The sentence is not talking about customs; it’s about a smart technique. Reject.(D) Bravery
Bravery is courage, but the sentence is not emphasizing courage; it’s focusing on problem-solving skill. Reject.
So the correct answer is (B) Cleverness.
Question 20: Where should the sentence be inserted?
The sentence is:
“This is all the more remarkable considering the lack of technology at the time.”
For sentence insertion questions, you always want to use clues. With clear clues, the answer becomes logically certain; without them, you can feel stuck and go in circles. In Dr. Byrns’s TOEFL Reading course, you learn three main types of clues for sentence insertion, derived from all the official ETS TOEFL sentence insertion questions, plus comprehensive strategy lectures, practice exercises, and a full set of previous official TOEFL Reading passages, questions, and answers. You can check out Dr. Byrns’s TOEFL Reading course at www.nanheebyrns.com
Now, coming back to our task:
Clue 1: “This”
“This” is a demonstrative pronoun, so it must refer back to an idea in the previous sentence. That means the target sentence has to come after the sentence that introduces the idea.Clue 2: “is all the more remarkable”
The linking verb “is” tells us “This” = something very remarkable. The phrase “all the more remarkable” means the earlier sentence already described something remarkable, and now the writer is emphasizing it even more.
So the target sentence should come right after a sentence that says something like “X was remarkable.”
Right before spot (A), the passage literally says that the Vikings’ navigation was remarkably precise. That’s exactly what we need:
Sentence 1: Their navigation was remarkable.
Sentence 2 (insertion): This is even more remarkable because they had no technology.
Here, “This” clearly refers to their precise navigation, and the logic flows smoothly:
remarkable ability → even more remarkable given no technology.
So the correct answer is (A).