ISEE Lower Level Reading : Identifying and Analyzing Main Idea and Theme in Science Passages

Study concepts, example questions & explanations for ISEE Lower Level Reading

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Example Questions

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Example Question #21 : Critical Comprehension

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?

Possible Answers:

"Other animals, called “K-strategists,” take greater pain in the rearing and upbringing of the young"

"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"

"Large broods indicate an “r” life strategy"

"Many different types of animals employ one of two strategies in raising their young."

"K-strategists produce half a dozen young, or less, but bring a large proportion of these on an average up to years of discretion"

Correct answer:

"Many different types of animals employ one of two strategies in raising their young."

Explanation:

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.

Example Question #1 : Determining Authorial Purpose In Narrative Science Passages

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 __________.

Possible Answers:

to describe how woodpeckers build their nests

to outline the unusual behavior of woodpeckers

to argue against the needless slaughter 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

Correct answer:

to describe how woodpeckers build their nests

Explanation:

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.

Example Question #11 : 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 __________.

Possible Answers:

Iron is a durable and tough substance that has long been used to wage war and construct buildings.

The wholesale destruction of the environment required to mine iron renders iron less useful than it otherwise would be.

The large amount of iron in the world is of great importance and benefit to mankind.

Man has a complex relationship with iron.

Without iron, mankind would be forced to rely on less useful metals, such as copper or bronze.

Correct answer:

The large amount of iron in the world is of great importance and benefit to mankind.

Explanation:

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.

Example Question #11 : Identifying And Analyzing Main Idea And Theme In Science Passages

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 __________.

Possible Answers:

to provide a brief overview of the nature and history of bears

to argue against commonly understood myths about bears

to explain the evolutionary history of bears

to argue in favor of increased awareness of bear conservation

to argue in favor of widespread bear culling

Correct answer:

to provide a brief overview of the nature and history of bears

Explanation:

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.

Example Question #21 : Critical Comprehension

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?

Possible Answers:

They provide food for birds, maintaining bird populations around the world.

They demonstrate intelligence, providing evidence of non-human sentience.

They recycle the surface layer of soil, keeping it fresh and fertile.

They consume waste, keeping the earth clean and healthy.

They break up rocks, keeping the earth level and flat.

Correct answer:

They recycle the surface layer of soil, keeping it fresh and fertile.

Explanation:

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.

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