SSAT Middle Level Reading : Recognizing the Main Idea in Argumentative Science Passages

Study concepts, example questions & explanations for SSAT Middle Level Reading

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Example Questions

Example Question #1 : Recognizing The Main Idea In Argumentative Science Passages

Adapted from "The Colors of Animals" by Sir John Lubbock in A Book of Natural History (1902, ed. David Starr Jordan)

The color of animals is by no means a matter of chance; it depends on many considerations, but in the majority of cases tends to protect the animal from danger by rendering it less conspicuous. Perhaps it may be said that if coloring is mainly protective, there ought to be but few brightly colored animals. There are, however, not a few cases in which vivid colors are themselves protective. The kingfisher itself, though so brightly colored, is by no means easy to see. The blue harmonizes with the water, and the bird as it darts along the stream looks almost like a flash of sunlight.

Desert animals are generally the color of the desert. Thus, for instance, the lion, the antelope, and the wild donkey are all sand-colored. “Indeed,” says Canon Tristram, “in the desert, where neither trees, brushwood, nor even undulation of the surface afford the slightest protection to its foes, a modification of color assimilated to that of the surrounding country is absolutely necessary. Hence, without exception, the upper plumage of every bird, and also the fur of all the smaller mammals and the skin of all the snakes and lizards, is of one uniform sand color.”

The next point is the color of the mature caterpillars, some of which are brown. This probably makes the caterpillar even more conspicuous among the green leaves than would otherwise be the case. Let us see, then, whether the habits of the insect will throw any light upon the riddle. What would you do if you were a big caterpillar? Why, like most other defenseless creatures, you would feed by night, and lie concealed by day. So do these caterpillars. When the morning light comes, they creep down the stem of the food plant, and lie concealed among the thick herbage and dry sticks and leaves, near the ground, and it is obvious that under such circumstances the brown color really becomes a protection. It might indeed be argued that the caterpillars, having become brown, concealed themselves on the ground, and that we were reversing the state of things. But this is not so, because, while we may say as a general rule that large caterpillars feed by night and lie concealed by day, it is by no means always the case that they are brown; some of them still retaining the green color. We may then conclude that the habit of concealing themselves by day came first, and that the brown color is a later adaptation.

Which of these statements best captures the main idea of this essay?

Possible Answers:

The color of an animal is not coincidental, but is an adaptation developed over time to aid its survival.

The coloring of animals changes widely over time and in different parts of the world.

The coloring of mature caterpillars is very difficult to explain without considering the behavior patterns they exhibit.

Animals inherit their coloring from their parents and pass on the same genes to their offspring.

The color of an animal is owed, at least in part, to its relationship with the environment in which it lives.

Correct answer:

The color of an animal is not coincidental, but is an adaptation developed over time to aid its survival.


The overall argument of this essay is that the coloring of animals is not coincidental, and that every animal is a specific color for a reason. Either the coloring matches with the environment to offer the animal some protection, or else it somehow supports the animal’s behavioral patterns. This idea is most clearly stated by the author in the opening sentence where he says, "The color of animals is by no means a matter of chance; it depends on many considerations . . . "

Example Question #171 : Science Passages

Adapted from “The Stars” by Sir Robert S. Ball in Wonders of Earth, Sea, and Sky (1902, ed. Edward Singleton Holden)

The group of bodies that cluster around our sun forms a little island in the extent of infinite space. We may illustrate this by drawing a map in which we shall endeavor to show the stars placed at their proper relative distances. 

We first open the compasses one inch, and thus draw a little circle to represent the path of Earth. We are not going to put in all the planets; we take Neptune, the outermost, at once. To draw its path, I open the compasses to thirty inches, and draw a circle with that radius. That will do for our solar system, though the comets no doubt will roam beyond these limits. 

To complete our map, we ought to put in some stars. There are a hundred million to choose from, and we shall begin with the brightest. It is often called the Dog Star, but astronomers know it better as Sirius. Let us see where it is to be placed on our map. Sirius is a good deal further off than Neptune; so I try at the edge of the drawing-board; I have got a method of making a little calculation that I do not intend to trouble you with, but I can assure you that the results it leads me to are quite correct; they show me that this board is not big enough. But could a board which was big enough fit into this lecture theatre? No; in fact, the board would have to go out through the wall of the theatre, out through London. Indeed, big as London is, it would not be large enough to contain the drawing-board that I should require. It would have to stretch about twenty miles from where we are now assembled. We may therefore dismiss any hope of making a practical map of our system on this scale if Sirius is to have its proper place. 

Let us, then, take some other star. We shall naturally try with the nearest of all. It is one that we do not know in this part of the world, but those that live in the southern hemisphere are well acquainted with it. The name of this star is Alpha Centauri. Even for this star, we should require a drawing three or four miles long if the distance from the earth to the sun is to be taken as one inch. 

You see what an isolated position our sun and its planets occupy. The stars might be very troublesome neighbors if they were very much closer to our system; it is therefore well they are so far off. If they were near at hand, they would drag us into unpleasantly great heat by bringing us too close to the sun, or produce a coolness by pulling us away from the sun, which would be quite as disagreeable.

Which of these characteristics of the universe is the author of this essay primarily concerned with convincing his audience of?

Possible Answers:

Its brilliance

Its destructive capabilities

Its isolation.

Its uniqueness

Its vastness

Correct answer:

Its vastness


In this essay, the author is trying to convince his audience primarily of the “vastness” of the universe. “Vast” means huge, expansive, and boundless. It might be reasonable to infer from the conclusion of the sentence where the author talks about the destruction that could be wrought on our world if the universe were closer together that the author wishes to highlight the universe’s “destructive capabilities,” but this is better understood as part of the author’s highlighting of the hugeness of the universe. In the passage, he is trying to show you how “vast” the universe is by demonstrating how impossible it is to render the universe on an accurate scaled-down model.

Example Question #1 : Main Ideas In Natural Science Passages

Adapted from The Principles of Breeding by S. L. Goodale (1861)

The Jersey cow, formerly known as the Alderney, is almost exclusively employed for dairy purposes, and may not be expected to give satisfaction for other uses. Their milk is richer than that of any other cows, and the butter made from it possesses a superior flavor and a deep rich color, and consequently commands an extraordinary price in all markets where good butter is appreciated.

Jersey cattle are of Norman origin, and are noted for their milking properties. The cows are generally very docile and gentle, but the males when past two or three years of age often become vicious and unmanageable. It is said that the cows fatten readily when dry.

There is no branch of cattle husbandry which promises better returns than the breeding and rearing of milch cows. In the vicinity of large towns and cities are many cows which having been culled from many miles around, on account of dairy properties, are considerably above the average, but taking the cows of the country together they do not compare favorably with the oxen. Farmers generally take more pride in their oxen, and strive to have as good or better than any of their neighbors, while if a cow will give milk enough to rear a large steer calf and a little besides, it is often deemed satisfactory.

The main purpose of this article is __________.

Possible Answers:

to argue against the use of dairy cows for meat

to explain the basics of animal husbandry

to describe the properties of the Jersey cow

to encourage the breeding of dairy cows

to reflect on the differences between various cows in England

Correct answer:

to encourage the breeding of dairy cows


In the first two paragraphs, the author primarily describes the properties of the Jersey cow, but his reason for doing so is to make an argument encouraging the greater selective breeding of dairy cows. This can be seen, for example, when the author says “There is no branch of cattle husbandry which promises better returns than the breeding and rearing of milch cows.” You can then see how the third paragraph is primarily a discussion of how farmers err by not focusing more of their attention in selectively breeding their dairy cows.

Example Question #1 : Comparing And Contrasting In Natural Science Passages

Adapted from “Some Strange Nurseries” by Grant Allen in A Book of Natural History (1902, ed. David Starr Jordan)

Among the larger lizards, a distinct difference may be observed between the American alligator and its near ally, the African crocodile. On the banks of the Mississippi, the alligator lays a hundred eggs or thereabouts, which she deposits in a nest near the water’s edge, and then covers them up with leaves and other decaying vegetable matter. The fermentation of these leaves produces heat and so does for the alligator’s eggs what sitting does for those of hens and other birds: the mother deputes her maternal functions, so to speak, to a festering heap of decomposing plant-refuse. Nevertheless, she loiters about all the time to see what happens, and when the eggs hatch out, she leads her little ones down to the river, and there makes alligators of them. This is a simple nursery arrangement of the big lizards.

The African crocodile, on the other hand, does something different, and takes greater care for the safety of its young. It lays only about thirty eggs, but these it buries in warm sand, and then lies on top of them at night, both to protect them from attack and to keep them warm during the cooler hours. In short, it sits upon them. When the young crocodiles within the eggs are ready to hatch, they utter an acute cry. The mother then digs down to the eggs, and lays them freely on the surface, so that the little reptiles may have space to work their way out unimpeded. This they do by biting at the shell with a specially developed tooth; at the end of two hours’ nibbling they are free, and are led down to the water by their affectionate parent. In these two cases we see the beginnings of the instinct of hatching, which in birds has become almost universal.

How does the author of this passage compares the American alligator and the African crocodile in terms of __________.

Possible Answers:

how closely-related each type of animal is to birds

how caring and protective the mothers are of their offspring

how much food is needed to keep the young of the animal alive

None of these answers is accurate.

how uncaring and protective the mothers are of their offspring

Correct answer:

how uncaring and protective the mothers are of their offspring


From the context of the whole of this passage, which is discussing the differences between how alligators and crocodiles care for their young, it is clear that the author believes that the American alligator is far less protective of its young than the African crocodile is, so the two animals are being compared in terms of "how caring and protective the mothers are of their young."

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