Text Summary questions will make you grateful for the time you’ve spent outlining readings and essays (if you haven’t done that, it’s a good idea!). To answer a Text Summary question, you’ll have to read and understand the entire passage and be able to distinguish between major and minor ideas.
After you read the passage, you will be given a topic sentence that summarizes the passage. There will be five answer choices, and you should pick the three that summarize the most important ideas of the passage. The order in which you choose the ideas does not matter. Partial credit is possible on these questions, so if you choose one incorrect answer, you can still earn one point (two points are possible).
There are two traps you can fall into in a text summary question. The first and most obvious is to choose an answer choice that contains incorrect information or that is not stated in the passage at all. The other is to choose a minor rather than a major idea. Try the example below to see what I mean.
Directions: Read the passage below and answer the question.
Paleontologists have argued for a long time that the demise of the dinosaurs was caused by climatic alterations associated with slow changes in the positions of continents and seas resulting from plate tectonics. Off and on throughout the Cretaceous (the last period of the Mesozoic era, during which dinosaurs flourished), large shallow seas covered extensive areas of the continents. Data from diverse sources, including geochemical evidence preserved in seafloor sediments, indicate that the Late Cretaceous climate was milder than today’s. The days were not too hot, nor the nights too cold. The summers were not too warm, nor the winters too frigid. The shallow seas on the continents probably buffered the temperature of the nearby air, keeping it relatively constant.
At the end of the Cretaceous, the geological record shows that these seaways retreated from the continents back into the major ocean basins. No one knows why. Over a period of about 100,000 years, while the seas pulled back, climates around the world became dramatically more extreme: warmer days, cooler nights; hotter summers, colder winters. Perhaps dinosaurs could not tolerate these extreme temperature changes and became extinct.
If true, though, why did cold-blooded animals such as snakes, lizards, turtles, and crocodiles survive the freezing winters and torrid summers? These animals are at the mercy of the climate to maintain a livable body temperature. It’s hard to understand why they would not be affected, whereas dinosaurs were left too crippled to cope, especially if, as some scientists believe, dinosaurs were warm-blooded. Critics also point out that the shallow seaways had retreated from and advanced on the continents numerous times during the Mesozoic, so why did the dinosaurs survive the climatic changes associated with the earlier fluctuations but not with this one? Although initially appealing, the hypothesis of a simple climatic change related to sea levels is insufficient to explain all the data.
Dissatisfaction with conventional explanations for dinosaur extinctions led to a surprising observation that, in turn, has suggested a new hypothesis. Many plants and animals disappear abruptly from the fossil record as one moves from layers of rock documenting the end of the Cretaceous up into rocks representing the beginning of the Cenozoic (the era after the Mesozoic). Between the last layer of Cretaceous rock and the first layer of Cenozoic rock, there is often a thin layer of clay. Scientists felt that they could get an idea of how long the extinctions took by determining how long it took to deposit this one centimeter of clay and they thought they could determine the time it took to deposit the clay by determining the amount of the element iridium (Ir) it contained.
Ir has not been common at Earth’s surface since the very beginning of the planet’s history. Because it usually exists in a metallic state, it was preferentially incorporated in Earth’s core as the planet cooled and consolidated. Ir is found in high concentrations in some meteorites, in which the solar system’s original chemical composition is preserved. Even today, microscopic meteorites continually bombard Earth, falling on both land and sea. By measuring how many of these meteorites fall to Earth over a given period of time, scientists can estimate how long it might have taken to deposit the observed amount of Ir in the boundary clay. These calculations suggest that a period of about one million years would have been required. However, other reliable evidence suggests that the deposition of the boundary clay could not have taken one million years. So the unusually high concentration of Ir seems to require a special explanation.
In view of these facts, scientists hypothesized that a single large asteroid, about 10 to 15 kilometers across, collided with Earth, and the resulting fallout created the boundary clay. Their calculations show that the impact kicked up a dust cloud that cut off sunlight for several months, inhibiting photosynthesis in plants; decreased surface temperatures on continents to below freezing; caused extreme episodes of acid rain; and significantly raised long-term global temperatures through the greenhouse effect. This disruption of food chain and climate would have eradicated the dinosaurs and other organisms in less than fifty years.
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.
Write your answer choices in the spaces where they belong. You can either write the letter of your answer choice or you can copy the sentence.
- The reason for dinosaurs’ extinction is unknown and continues to fuel debate among scientists.
(A) Extreme changes in daily and seasonal climates preceded the retreat of the seas back into the major ocean basins.
(B) A simple climate change does not explain some important data related to the extinction of the dinosaurs at the end of the Cretaceous.
(C) The retreat of the seaways at the end of the Cretaceous has not been fully explained.
(D) The abruptness of extinctions at the end of the Cretaceous and the high concentration of Ir found in clay deposited at that time have fueled the development of a new hypothesis.
(E) Some scientists hypothesize that the extinction of the dinosaurs resulted from the effects of an asteroid collision with Earth.
(F) Boundary clay layers like the one between the Mesozoic and Cenozoic are used by scientists to determine the rate at which an extinct species declined.
The correct answers are B, D, and E. A is not true: the extreme changes in climate occurred at the same time as the retreat of the seas. C is true, but the retreat of the seaways is not as important in the passage as the ideas directly related to the dinosaurs’ demise. F is probably true, but the passage doesn’t deal with the Mesozoic period: it deals with the Cenozoic and Cretaceous periods.