ISEE Lower Level Reading Comprehension › Identifying and Analyzing Main Idea and Theme in Science Passages
Adapted from A Catechism of Familiar Things: Their History and the Events Which Led to Their Discovery by the Benziger Brothers (1881)
Iron is one of the most useful and abundant metals, being found in all mineral earths, stones, plants, and animal fluids. Iron is found in great masses, in various states, in the bowels of the earth; it is usually, however, compounded with stone, from which it is separated by the action of fire. In some parts of the world, whole mountains are formed of iron; among these may be mentioned the Pilot Knob and the Iron Mountain, in Missouri, being unsurpassed by anything of the kind found elsewhere.
It is hard, fusible, not very malleable, but extremely ductile, and very tenacious; it is of a greyish color, and nearly eight times heavier than water. Without iron, society could make no progress in the cultivation of the ground, in mechanical arts or trades, in architecture or navigation; it is therefore of the greatest use to man.
The primary argument of this essay is that __________.
The large amount of iron in the world is of great importance and benefit to mankind.
Iron is a durable and tough substance that has long been used to wage war and construct buildings.
Without iron, mankind would be forced to rely on less useful metals, such as copper or bronze.
Man has a complex relationship with iron.
The wholesale destruction of the environment required to mine iron renders iron less useful than it otherwise would be.
The author is making two points in this essay. Firstly, he says that there is a large quantity of iron in the world. This can be seen in excerpts such as “Iron is found in great masses, in various states, in the bowels of the earth." Secondly, he says that this great quantity of iron is of great importance and benefit to mankind. This second point can be seen in statements such as “Without iron, society could make no progress" and "it is therefore of the greatest use to man.” The correct answer is therefore the one that reflects the author’s two main points and the relationship between the two—there is a lot of iron, and mankind needs iron, so it is important that there is a lot of iron.
"The Multiple Sides of Computer Science" by Matthew Minerd (2014)
It often takes some time for a new discipline to become recognized as an independent science. An excellent example of this is computer science. In many ways, this science still is a hodgepodge of several different sciences, each one having its own distinct character. For example, some computer scientists are almost indistinguishable from mathematicians. Many of the most difficult topics in pattern recognition and data communications require intensive mathematics in order to provide software solutions. Years of training in the appropriate disciplines are necessary before the computer scientist can even begin to work as a programmer in such areas. In contrast to those computer scientists who work with complex mathematics, many computer scientists work on areas of hardware development that are similar to disciplines like electrical engineering and physics.
However, computer science has its own particular problems regarding the unity of its subject matter. There are many practical applications for computing work; therefore, many computer scientists focus on learning a large set of skills in programming languages, development environments, and even information technology. All of these disciplines have a certain practical coloration that is quite distinct from the theoretical concepts used in other parts of the field. Nevertheless, these practical topics add to the broad range of topics covered by most academic programs that claim to focus on “computer science.” It can only be hoped that these disciplines will increase in orderliness in the coming decades.
What will be the effect of increased orderliness in computer science studies?
It will be easier to understand the distinct topic studied in computer science
It will make scheduling much easier for most students
It will allow for greater progress in experimentation
It will help to overcome biases against practical applications of computer science
It will set to rest the debates about computer science's importance
The main focus of this whole passage is the fact that it is hard to figure out the single thing studied by computer science. It has many branches, all of which seem to be rather different and unrelated (or at least not very related). With increased orderliness, we can assume that it will become clearer just what is the special topic studied in computer science—as opposed to mathematics, physics, or information technology.
Adapted from "How the Soil is Made" by Charles Darwin in Wonders of Earth, Sea, and Sky (1902, ed. Edward Singleton Holden)
Worms have played a more important part in the history of the world than most persons would at first suppose. In almost all humid countries they are extraordinarily numerous, and for their size possess great muscular power. In many parts of England a weight of more than ten tons (10,516 kilograms) of dry earth annually passes through their bodies and is brought to the surface on each acre of land, so that the whole superficial bed of vegetable mould passes through their bodies in the course of every few years. From the collapsing of the old burrows, the mold is in constant though slow movement, and the particles composing it are thus rubbed together. Thus the particles of earth, forming the superficial mold, are subjected to conditions eminently favorable for their decomposition and disintegration. This keeps the surface of the earth perfectly suited to the growth of an abundant array of fruits and vegetables.
Worms are poorly provided with sense-organs, for they cannot be said to see, although they can just distinguish between light and darkness; they are completely deaf, and have only a feeble power of smell; the sense of touch alone is well developed. They can, therefore, learn little about the outside world, and it is surprising that they should exhibit some skill in lining their burrows with their castings and with leaves, and in the case of some species in piling up their castings into tower-like constructions. But it is far more surprising that they should apparently exhibit some degree of intelligence instead of a mere blind, instinctive impulse, in their manner of plugging up the mouths of their burrows. They act in nearly the same manner as would a man, who had to close a cylindrical tube with different kinds of leaves, petioles, triangles of paper, etc., for they commonly seize such objects by their pointed ends. But with thin objects a certain number are drawn in by their broader ends. They do not act in the same unvarying manner in all cases, as do most of the lower animals.
What “important part in the history of the world” does the author believe worms have played?
They recycle the surface layer of soil, keeping it fresh and fertile.
They break up rocks, keeping the earth level and flat.
They consume waste, keeping the earth clean and healthy.
They provide food for birds, maintaining bird populations around the world.
They demonstrate intelligence, providing evidence of non-human sentience.
The first paragraph is essentially one long explanation about the very important role that worms have played in history of the world. The author begins by saying “Worms have played a more important part in the history of the world than most persons would at first suppose.” The author then goes on to describe the process by which they play this “important part.” And, finally, he concludes by saying “This keeps the surface of the earth perfectly suited to the growth of an abundant array of fruits and vegetables.” The key is to focus on the relationship between the opening and closing sentences of the first paragraph.
"Abstraction in the Sciences" by Matthew Minerd (2014)
Thinking “abstractly” is not a term that means quite the same thing in all of the sciences. Although we rarely think about this, it plays a key role in almost all of our day-to-day thought. Consider a zoologist working in a lab with many animals. When she is studying any individual tiger, she is not completely worried about the particular tiger—at least not primarily. Instead, she is trying to figure out certain characteristics of tigers in general. By meticulous testing, the zoologist carefully works out the physiology of tigers and considers what are absolutely necessary elements of their physical makeup. Even when she places a tiger in different habitats, her sight is aimed at the general condition of tigers and their needs in general.
However, things become even stranger when you start to consider how we think about mathematical objects. Consider the case of geometric figures. A triangle appears to be rather simple for most of us to think about. You can draw a triangle on a piece of paper, each side having a certain thickness and length. However when you think about this in geometry class, the triangle’s edges have no real thickness. Neither a point nor a line has a thickness for the mathematician. Such a thickness only exists on our paper, which represents the point or line. Consider also a line drawn on a piece of graph paper. Technically, there are an infinite number of points in the line. Indeed, even between 4.5 and 4.6, there are an infinite number of numbers—for example 4.55 is between them, then 4.555 between 4.55 and 4.6, and 4.5555 between 4.555 and 4.6, et cetera. In all of these cases, the mathematical reality takes on a very peculiar character when you consider it in the abstract. However, the concrete triangle remains very tangible and ordinary. Likewise, 4.6 and 4.5 inches still have 0.1 inches between them. Nevertheless, in the abstract, mathematical realities are quite strange, even stranger then the idea of “a tiger in general.”
Which of the following would strengthen the ending of the first paragraph?
"The details of any particular tiger’s life are interesting only as a means to this end."
"Each individual tiger has its own unique characteristics and abilities."
"Of course, she becomes quite attached to all of the animals in her care."
"Every animal is carefully tested as a potential test subject."
None of the other answers
As written, the last sentence in the first paragraph states that the scientist is interested in figuring out what "tigers in general" are like. Therefore, any particular tiger is not as important as this general nature of tigers (how they generally can live, thrive, etc). The best way to end this paragraph is by reiterating this point, which is what the correct answer does.
Adapted from "Some Strange Nurseries" by Grant Allen in A Book of Natural History (1902, ed. David Starr Jordan)
Many different types of animals employ one of two strategies in raising their young. Certain animals, called “r-strategists,” turn out thousands of eggs with reckless profusion, but they let them look after themselves, or be devoured by enemies, as chance will have it. Other animals, called “K-strategists,” take greater pain in the rearing and upbringing of the young. Large broods indicate an “r” life strategy; small broods imply a “K” life strategy and more care in the nurture and education of the offspring. R-strategists produce eggs wholesale, on the off chance that some two or three among them may perhaps survive an infant mortality of ninety-nine per cent, so as to replace their parents. K-strategists produce half a dozen young, or less, but bring a large proportion of these on an average up to years of discretion.
Which of these extracts best captures the main idea of this passage?
"Many different types of animals employ one of two strategies in raising their young."
"Other animals, called “K-strategists,” take greater pain in the rearing and upbringing of the young"
"Large broods indicate an “r” life strategy"
"K-strategists produce half a dozen young, or less, but bring a large proportion of these on an average up to years of discretion"
"R-strategists produce eggs wholesale, on the off chance that some two or three among them may perhaps survive an infant mortality of ninety-nine per cent, so as to replace their parents"
The main idea of this essay is that there is a direct correlation between the number of offspring a species generally produces and the type of life strategy that species employs. This idea is really only captured in the first sentence, ""Many different types of animals employ one of two strategies in raising their young." Another sentence might be better if it compared both r-strategists and K-strategists, but the other four answer choices are less succinct and direct, and usually only make half the author’s point.
Adapted from Chatterbox Stories of Natural History by R. Worthington (1880)
The guinea pig is a native of South America, and is remarkable for the beauty and variety of its colors and the neatness of its appearance. These little pets are very careful in keeping themselves and their offspring neat and tidy, and may be frequently seen smoothing and dressing their fur, somewhat in the manner of a cat. After having smoothed and dressed each other's fur, both turn their attention to their young, from whose coats they remove the smallest speck of dirt, at the same time trying to keep their hair smooth and unruffled. The guinea pig feeds on bread, grain, fruit, vegetables, tea leaves, and especially garden parsley, to which it is very partial. It generally gives birth to seven and eight young at a time, and they very soon are able to take care of themselves.
The main point of this passage is __________.
to provide a brief overview of guinea pigs
to describe what guinea pigs like to eat
to explain where guinea pigs come from
to argue that guinea pigs make good pets
to outline how guinea pigs care for their young
There is no evidence to suggest the author is arguing anything in this passage, so we know this is not about whether or not guinea pigs make good pets. The correct answer choice is that the point of this passage is "to provide a brief overview of guinea pigs.” The author talks about what they like to eat, where they come from, how they care for their young, but each of these is part of the author’s attempts to briefly describe guinea pigs.
Adapted from Anecdotes of the Habits and Instincts of Animals by Mrs. R. Lee (1852)
The Carnivora are divided by naturalists into three groups, the characters of which are taken from their feet and manner of walking. Bears rank among the Plantigrada, or those which put the whole of their feet firmly upon the ground when they walk. They are occasionally cunning and ferocious, but often evince good humor and a great love of fun. In their wild state, they are solitary the greater part of their lives. They climb trees with great facility; live in caverns, holes, and hollow trees; and in cold countries, retire to some sequestered spot during the winter, where they remain concealed and bring forth their young. Some say they are torpid, but this cannot be, for the female bears come from their retreats with cubs that have lived upon them, and it is not likely that they can have reared them and remained without food; they are, however, often very lean and wasted, and the absorption of their generally large portion of fat contributes to their nourishment. The story that they live by sucking their paws is, as may be supposed, a fable; when well-fed they always lick their paws, very often accompanying the action with a peculiar sort of mumbling noise. There are a few which will never eat flesh, and all are able to do without it. They are, generally speaking, large, clumsy, and awkward, possessing large claws for digging, and often walk on their hind feet, a facility afforded them by the peculiar formation of their thigh bone. They do not often attack in the first instance, unless impelled by hunger or danger; they are, however, formidable opponents when excited. In former times, there were few parts of the globe in which they were not to be found, but, like other wild animals, they have disappeared before the advance of man. Still they are found in certain spots from the northern regions of the world to the burning climes of Africa, Asia, and America. The latest date of their appearance in Great Britain was in Scotland during the year 1057.
The main point of this passage is __________.
to provide a brief overview of the nature and history of bears
to explain the evolutionary history of bears
to argue against commonly understood myths about bears
to argue in favor of widespread bear culling
to argue in favor of increased awareness of bear conservation
The author can only be said to take up an argumentative structure at one point in the passage, when she discusses whether or not bears are "torpid" and says "this cannot be" before explaining her reasoning. However, the rest of the passage provides information in a non-argumentative way. You could perhaps infer from the author’s comment that bears have disappeared before the “advance of man” that she is arguing in favor of bear conservation, but that sentence is the only one that considers bear conservation, and it is stated matter-of-factly, not in an argumentative tone. The best answer here is that this passage intends to “provide a brief overview of the nature and history of bears.” This can be seen throughout with the way the bear explains their scientific classification, their hibernation habits, and their decline in numbers around the world.
Adapted from "Bats" by W. S. Dallas in A Book of Natural History (1902, ed. David Starr Jordan)
Like the owls, with which they share the dominion of the evening air, the bats have a perfectly noiseless flight; their activity is chiefly during the twilight, although some species are later, and in fact seem to keep up throughout the whole night. As they rest during the day, concealed usually in the most inaccessible places they can find, and are seen only upon the wing, their power of flight is their most striking peculiarity in the popular mind, and it is perhaps no great wonder that by many people, both in ancient and modern times, they have been regarded as birds. Nevertheless, their hairy bodies and leathery wings are so unlike anything that we ordinarily understand as pertaining to a bird, that opinion was apparently always divided, as to the true nature of these creatures—“a mouse with wings,” as Goldsmith called it once, according to James Boswell, is certainly a curious animal, and very difficult to classify so long as the would-be systematist has no particularly definite ideas to guide him. The likeness of the bat to a winged mouse has made itself felt in the name given to the creature in many languages, such as the “chauvesouris” of the French and the “flitter-mouse” of some parts of England, the latter being reproduced almost literally in German, Dutch, and Swedish, while the Danes called the bat a “flogenmues,” which has about the same meaning.
Throughout this passage the author primarily highlights the __________ nature of bats.
mysterious
abrasive
calculating
unruly
nocturnal
At various parts of this passage, the author highlights the “mysterious" nature of bats. Although he does briefly mention the “nocturnal” (sleeping during the day and being awake at night) nature of bats, as when he says “their activity is chiefly during the twilight, although some species are later, and in fact seem to keep up throughout the whole night," this is not the primary focus. Examples of the author highlight the “mysterious” nature of bats can be seen when he says, “As they rest during the day, concealed usually in the most inaccessible places they can find,“ and “their power of flight is their most striking peculiarity in the popular mind,“ and “Nevertheless, their hairy bodies and leathery wings are so unlike anything that we ordinarily understand as pertaining to a bird, that opinion was apparently always divided, as to the true nature of these creatures.”
Adapted from "Sea-slugs and Cuttlefish" by Charles Darwin in A Book of Natural History (1902, ed. David Starr Jordan)
I was much interested, on several occasions, by watching the habits of a cuttlefish. Although common in the pools of water left by the retiring tide, these animals were not easily caught. By means of their long arms and suckers, they could drag their bodies into very narrow crevices; and when thus fixed, it required great force to remove them. At other times they darted, with the rapidity of an arrow, from one side of the pool to the other, at the same instant discoloring the water with a dark chestnut-brown ink. These animals also escape detection by a very extraordinary, chameleon-like power of changing their color. They appear to vary their tints according to the nature of the ground over which they pass: when in deep water, their general shade was brownish-purple, but when placed on the land, or in shallow water, this dark tint changed into one of a yellowish green.
This cuttlefish displayed its chameleon-like power both during the act of swimming and whilst remaining stationary at the bottom. I was amused by the various arts to escape detection used by one individual, which seemed fully aware that I was watching it. Remaining for a time motionless, it would then stealthily advance an inch or two, like a cat after a mouse; sometimes changing its color, it proceeded, till having gained a deeper part, it darted away, leaving a dusky train of ink to hide the hole into which it had crawled.
The main idea of this passage is that __________.
Cuttlefish have many different abilities that help them to avoid capture.
The author is very interested in the habits of cuttlefish.
The author has never successfully caught a cuttlefish.
Cuttlefish are very small and agile creatures.
Cuttlefish are very common in the rock pools near where the author lives.
The main idea of this passage is that cuttlefish are very difficult to catch because they have many different skills that allow them to avoid capture. The author talks about their “chameleon-like power of changing their color,” their “long arms and suckers” with which “they could drag their bodies into very narrow crevices,” and their ability to dart “with the rapidity of an arrow, from one side of the pool to the other, at the same instant discoloring the water with a dark chestnut-brown ink.” The main thesis of the text is probably “Although common in the pools of water left by the retiring tide, these animals were not easily caught.” The other answer choices are common features of this text, but not the main idea of the passage.
Adapted from "Birds’ Nests" by John Burroughs in A Book of Natural History (1902, ed. David Starr Jordan)
The woodpeckers all build in about the same manner, excavating the trunk or branch of a decayed tree, and depositing the eggs on the fine fragments of wood at the bottom of the cavity. Though the nest is not especially an artistic work, requiring strength rather than skill, yet the eggs and the young of few other birds are so completely housed from the elements, or protected from their natural enemies—the jays, crows, hawks, and owls. A tree with a natural cavity is never selected, but one which has been dead just long enough to have become soft and brittle throughout. The bird goes in horizontally for a few inches, making a hole perfectly round and smooth and adapted to his size, then turns downward, gradually enlarging the hole, as he proceeds, to the depth of ten, fifteen, twenty inches, according to the softness of the tree and the urgency of the mother bird to deposit her eggs. While excavating, male and female work alternately. After one has been engaged fifteen or twenty minutes, drilling and carrying out chips, it ascends to an upper limb, utters a loud call or two, when its mate soon appears, and, alighting near it on the branch, the pair chatter and caress a moment; then the fresh one enters the cavity and the other flies away.
The main purpose of this passage is __________.
to describe how woodpeckers build their nests
to outline the unusual behavior of woodpeckers
to highlight the close relationship between male and female woodpeckers
to examine the process by which a woodpecker chooses a tree for its nest
to argue against the needless slaughter of woodpeckers
From start to finish, this passage is about the process by which a woodpecker builds its nest. Although there is some discussion of the unusual behavior of woodpeckers, the close relationship between males and females, and a short examination into how a woodpecker chooses its nest, these three elements combine as part of the main purpose: describing the process of nest-building among woodpeckers.