The Truth About a Bird’s Eye View · 2020-02-19 · eye has its own lens, rods, and cones, and...

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The Truth About a Bird’s Eye View

by Anna Vlasits and Ryan Morrie

Have you ever wondered what it would be like to see through the eyes of a bird? What about a fly? Or your dog? Scientists who study animal eyes can find out what it would be like to see the world from an animal’s perspective by studying their behavior as well as the shapes and sizes of their eyes. In addition, they can study the inner parts of the eye, such as the lens, which focuses light, or the different types of cells that make up the eye. For example, rod and cone cells are special cells in the back of the eye that detect light and send the message that it is light out to the brain.

Here are some things scientists have learned from studying animals’ eyes—including some things you might not have imagined.

Fact or fiction?: A fly sees hundreds of images of the same thing with its eyes. Fiction!

Flies have eyes that are very different from ours. Their eyes are called compound eyes because each eye is actually hundreds of little eyes compounded together. Each little eye has its own lens, rods, and cones, and transmits a unique signal to the fly’s brain.

Though you may have heard differently, even though flies have compound eyes, they still see one image, just like us. This is because each little eye in the compound eye is pointed in a slightly different direction, so the light it senses is separate from the other little eyes.

The way a fly sees is similar to how a picture is formed on a computer. If you think of a picture on a computer, it is composed of many pixels that are in different places. Like the pixels in a picture on a computer, the information from the different little eyes gets put together to form an image. In this case, the fly’s brain puts all the information from the little eyes together to make one image of what the fly sees.



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Fact or fiction?: A dog can see me when it’s licking my face. It depends!

Dogs have different eyes depending on the breed of the dog. Small dogs are usually good at seeing things up close and can probably make out smiles and frowns on our faces. This is because small dogs were bred to be human companions and live inside. Those small dogs that were good at interacting with humans, probably because they could see their faces better, were more likely to be bred to make puppies.

In contrast, large dogs are good at seeing far away, but aren’t very good at seeing up close. These dogs were bred to do work outside, like hunting birds and rabbits or herding sheep. Breeders picked the dogs that were best at doing their work and over time most large dogs evolved good distance vision. To do this they sacrificed being able to see very well up close.

So why do big dogs come close up to greet you if they can see you better from far away? Dogs have a really great sense of smell and they approach humans in order to smell them!

Fact or fiction?: There are animals that can see more colors than a person. Fact!

Humans can only see three colors: red, green, and blue. All of the other colors we see are because of the combination of red, green, and blue light, similar to how you can create an orange painting with yellow and red paint. On the other hand, birds can detect four different colors with their eyes. In addition to seeing red, green, and blue, birds have a special type of cone cell that is activated when ultraviolet light shines on it.

Ultraviolet light, or UV light, is the light that comes out of a black light. More powerful versions of this type of light can give you a sunburn if you are at the beach without sunscreen.

Birds see ultraviolet light because it is important for mating and for finding their prey. Many birds have colorful patterns of feathers that reflect UV light to attract their mates. When the UV light reflects off the feathers, other birds that can see UV will see the reflections. Small prey also often leave trails of urine that reflect UV light. Birds can use their UV vision to track their prey when hunting.

Because we do not have receptors for UV light, we cannot see these patterns. However, other animals besides birds can also see UV light, like bees and fish. Many flowers reflect UV light in exciting patterns to attract bees so they will be pollinated.



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Fact or fiction?: Some animals can see even in the dark. Fiction!

Owls, raccoons, and cats are nocturnal because they are awake at night. Although it may seem like nocturnal animals are able to see in the dark, if it were completely dark, these animals would not be able to see at all.

Because vision is based upon light, without it there would be nothing to activate the rod and cone cells in the eye, so the animal would only see black. However, nocturnal animals are able to see in very dim light because they have special types of eyes.

One important part of being nocturnal is having bigger eyes. The bigger the eye, the more light can get in. Therefore there’s a higher chance of collecting light, and thus being able to see, at night. A human’s eye “gets bigger” in the dark too. When you go into a dark room your pupils will get bigger to let more light in. If you then hold up a mirror and turn on the light, you’ll see your pupils shrink.

Nocturnal animals’ eyes are also special because they have more rod cells. Rod cells are a type of cell that is better at sensing very small amounts of light. If you have more rods, you can see much better in dim light. Humans have rods too, but not as many as nocturnal animals do.

The final specialty for nocturnal animals is a reflective material in the back of their eyes that is like a mirror. You may have come across a dog or cat at night and seen light reflecting out of its eyes. In the same way that having big eyes helps an animal see in the dark, the mirror lets the eye collect more light by giving the rod and cone cells two chances to see the light, once when it passes into the eye and once more when it reflects off the mirror and comes back out.



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1 Which quote supports the central ideas that different animals have different abilities and humans do not have the best vision of all species?

A “For example, rod and cone cells are special cells in the back of the eye that detect light and send the message that it is light out to the brain.”

B “In contrast, large dogs are good at seeing far away, but aren’t very good at seeing up close.”

C “Birds see ultraviolet light because it is important for mating and for finding their prey.”

D “Although it may seem like nocturnal animals are able to see in the dark, if it were completely dark, these animals would not be able to see at all.”

2 What does the word compound mean in paragraph 3?

A attractive

B confusing

C ornamental

D combined

3 How does paragraph 5 contribute to the development of the text?

A It provides an example humans can relate to and understand.

B It explains why humans fail to understand how animals see.

C It illustrates how simple it is for humans to learn about insects’ vision.

D It conveys the desire humans have to learn about insects.



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4 Why does the author compare the fly’s sight to pixels on a computer?

A to create a relatable example that helps explain how the fly sees

B to emphasize the superiority of how the fly sees over the way a human sees

C to show that a fly is unable to see things in the world bigger than itself

D to communicate that a fly is able to see the world just like a human

5 Which quote supports the authors’ claim that nocturnal animals are incapable of seeing in total darkness?

A “Owls, raccoons, and cats are nocturnal because they are awake at night.”

B “Because vision is based upon light, without it there would be nothing to activate the rod and cone cells in the eye, so the animal would only see

black.”

C “One important part of being nocturnal is having bigger eyes.”

D “The final specialty for nocturnal animals is a reflective material in the back of their eyes that is like a mirror.”

6 Which quote explains how the difference in size of nocturnal animals’ eyes affects sight?

A “Owls, raccoons, and cats are nocturnal because they are awake at night.”

B “The bigger the eye, the more light can get in.”

C “If you then hold up a mirror and turn on the light, you’ll see your pupils shrink.”

D “You may have come across a dog or cat at night and seen light reflecting out of its eyes.”



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7 Which statement summarizes the text?

A Animal vision is different from human vision in significant ways based only upon the size of the eyes. Animals with larger eyes focus faster.

B Animal vision is different from human vision in significant ways. Vision can vary based on the size and shape of eyes and the kinds of eye cells.

C Animal vision is not significantly different from human vision unless the size of the eyes is different. Animals with smaller eyes focus better.

D Animal vision is not significantly different from human vision unless the animal is nocturnal. Nocturnal animals can see in true darkness.

8 How do the authors reveal their points of view in the text?

A by explaining the various ways different animals see colors

B by using complex data to explain their points

C by providing detailed descriptions of the anatomy of the eye

D by using casual language and relatable examples



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Adapted from Kidnapped: “The Islet”

by Robert Louis Stevenson

The time I spent upon the island is still so horrible a thought to me that I must pass it lightly over. In all the books I have read of people cast away, either they had their pockets full of tools, or a chest of things would be thrown upon the beach along with them, as if on purpose. My case was very much different. I had nothing in my pockets but money and Alan’s silver button; and being inland bred, I was as much short of knowledge as of means.

I knew indeed that shellfish were counted good to eat; and among the rocks of the isle I found a great plenty of limpets, which at first I could scarcely strike from their places, not knowing quickness to be needful. There were, besides, some of the little shells that we call buckies; I think periwinkle is the English name. Of these two I made my whole diet, devouring them cold and raw as I found them; and so hungry was I that at first they seemed to me delicious.

Perhaps they were out of season, or perhaps there was something wrong in the sea about my island. But at least I had no sooner eaten my first meal than I was seized with giddiness and retching, and lay for a long time no better than dead. A second trial of the same food (indeed, I had no other) did better with me and revived my strength.

But as long as I was on the island, I never knew what to expect when I had eaten; sometimes all was well, and sometimes I was thrown into a miserable sickness; nor could I ever distinguish what particular fish it was that hurt me. All day it streamed rain; there was no dry spot to be found; and when I lay down that night, between two boulders that made a kind of roof, my feet were in a bog.

From a little up the hillside over the bay I could catch a sight of the great ancient church and the roofs of the people’s houses in Iona. And on the other hand, over the low country of the Ross, I saw smoke go up, morning and evening, as if from a homestead in a hollow of the land.

I used to watch this smoke, when I was wet and cold and had my head half-turned with loneliness, and think of the fireside and of the company till my heart burned. Altogether, this sight I had of men’s homes and comfortable lives, although it put a point on my own sufferings, yet it kept hope alive, and helped me to eat my raw shellfish (which had soon



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grown to be a disgust), and saved me from the sense of horror I had whenever I was quite alone with dead rocks, and fowls, and the rain, and the cold sea.

Charles the Second declared a man could stay outdoors more days in the year in the climate of England than in any other. That was very like a king with a palace at his back and changes of dry clothes. But he must have had better luck on his flight from Worcester than I had on that miserable isle. It was the height of summer; yet it rained for more than twenty-four hours, and did not clear until the afternoon of the third day.

There is a pretty high rock on the northwest of Earraid, which (because it had a flat top and overlooked the Sound) I was much in the habit of frequenting; not that I ever stayed in one place, save when asleep, my misery giving me no rest. Indeed, I wore myself down with continual and aimless goings and comings in the rain.

As soon, however, as the sun came out, I lay down on the top of that rock to dry myself. The comfort of the sunshine is a thing I cannot tell. It set me thinking hopefully of my deliverance, of which I had begun to despair; and I scanned the sea and the Ross with a fresh interest. On the south of my rock a part of the island jutted out and hid the open ocean so that a boat could thus come quite near me upon that side and I be none the wiser.

Well, all of a sudden, a fishing boat, with a brown sail and a pair of fishers aboard it, came flying round that corner of the isle, bound for Iona. I shouted out, and then fell on my knees on the rock and prayed to them. They were near enough to hear—I could even see the color of their hair—and there was no doubt but they observed me, for they cried out in the Gaelic tongue, and laughed. But the boat never turned aside, and flew right on, before my eyes, for Iona.

I could not believe such wickedness, and ran along the shore from rock to rock, crying on them piteously; even after they were out of reach of my voice I still cried and waved to them; and when they were quite gone I thought my heart would burst.

The next day (which was the fourth of this horrible life of mine) I found my bodily strength run very low. But the sun shone, the air was sweet, and what I managed to eat of the shellfish agreed well with me and revived my courage.



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I was scarce back on my rock (where I went always the first thing after I had eaten) before I observed a boat coming down the Sound, and with her head, as I thought, in my direction.

9 Which quote supports the theme of pride in one’s country?

A “There were, besides, some of the little shells that we call buckies; I think periwinkle is the English name.”

B “And on the other hand, over the low country of the Ross, I saw smoke go up, morning and evening, as if from a homestead in a hollow of the land.”

C “Charles the Second declared a man could stay outdoors more days in the year in the climate of England than in any other.”

D “On the south of my rock a part of the island jutted out and hid the open ocean so that a boat could thus come quite near me upon that side and I be none the wiser.”

10 How does the isolated setting affect the narrator’s emotions?

A It creates a sense of daring adventure.

B It creates a sense of wary suspense.

C It creates a sense of unending loneliness.

D It creates a sense of amused delight.



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11 What is meant by the figurative language in the quote below from the first paragraph?

“I had nothing in my pockets but money and Alan’s silver button; and being inland bred, I was as much short of knowledge as of means.”

A He has neither the understanding nor the supplies to handle the situation.

B He has neither the wealth nor the training to understand the situation.

C He has classroom knowledge instead of actual experience.

D He has the tools he needs, but he does not know how to use them.

12 Which quote suggests that the narrator longs for his past?

A “In all the books I have read of people cast away, either they had their pockets full of tools, or a chest of things would be thrown upon the beach along with them, as if on purpose.”

B “Of these two I made my whole diet, devouring them cold and raw as I found them; and so hungry was I that at first they seemed to me delicious.”

C “All day it streamed rain; there was no dry spot to be found; and when I lay down that night, between two boulders that made a kind of roof, my feet were in a bog.”

D “I used to watch this smoke, when I was wet and cold and had my head half-turned with loneliness, and think of the fireside and of the company till my heart burned.”



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13 Which quote supports the idea that the narrator believes in positive thinking?

A “A second trial of the same food (indeed, I had no other) did better with me and revived my strength.”

B “Although it put a point on my own sufferings, yet it kept hope alive.”

C “As soon, however, as the sun came out, I lay down on the top of that rock to dry myself.”

D “And when they were quite gone I thought my heart would burst.”

14 What is the meaning of the phrase “till my heart burned” in paragraph 6?

A The narrator is gasping for breath because of the struggle and exertion.

B The narrator is overcome with emotion and longing for home.

C The narrator is sick from lack of nutrition and proper rest.

D The narrator is struggling to forget someone he once loved.

15 How do paragraphs 10 and 11 contribute to the theme of conflicting emotions?

A They underline the narrator’s sudden hope and then complete despair.

B They minimize the narrator’s complete discomfort and show his distrust.

C They emphasize the narrator’s inability to survive and lack of wisdom.

D They highlight the narrator’s ability to survive despite his lack of food.



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16 Which quote suggests that the narrator is determined?

A “The time I spent upon the island is still so horrible a thought to me that I must pass it lightly over.”

B “But as long as I was on the island, I never knew what to expect when I had eaten; sometimes all was well, and sometimes I was thrown into a miserable sickness; nor could I ever distinguish what particular fish it was that hurt

me.”

C “I used to watch this smoke, when I was wet and cold and had my head half-turned with loneliness, and think of the fireside and of the company till my heart burned.”

D “But the sun shone, the air was sweet, and what I managed to eat of the shellfish agreed well with me and revived my courage.”



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What Is Debt?

Have you ever borrowed money?

Have you ever wanted to buy something, but didn’t have quite enough money? If you’ve borrowed money from friends, family, or anyone else and promised to repay them, then you are “indebted” to pay it back. This is called “debt.”

Debt is money one person, organization, or government owes to another person, organization, or government. Typically, the person who borrows the money has a limited amount of time to pay back that money with interest (an additional amount you pay to use borrowed money).

Why do people, organizations, and businesses have debt?

People and businesses have debt because they need or want to buy something, but they don’t have enough money to pay for it at the time. Adults sometimes borrow a large amount of money to pay for a house, a car, college tuition, medical bills, or home repairs.

Credit cards are also a form of debt. If you purchase a pair of shoes by charging it on a credit card, you are in debt to the credit card company until you pay your bill. Businesses borrow money to help pay their employees and buy expensive items such as buildings, computers, and other large purchases.

Why does the U.S. government have debt?

The U.S. government is just like a business. The government has to provide services for the people of the United States such as military protection, education and health programs, the space program, and social services programs. It also needs money to buy supplies and equipment.

The government’s main source of money is the taxes it collects from individuals and businesses. There are different kinds of taxes. Here are some examples:

Income tax (money people pay to the government based on how much theyearn from their jobs)



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Sales and excise tax (money people pay to the government when they buythings)

Corporate tax (money businesses pay to the government based on theirearnings)

However, the amount of money the government spends to pay for the services it provides is often more than the taxes it collects. To make up the difference, the government borrows money—in other words, it goes into “debt.”

How does the U.S. government borrow money?

Here’s where the government is different from individual people and businesses. When the government borrows money, it doesn’t go to the bank and apply for a loan. It “issues debt.” This means the government sells Treasury marketable securities such as Treasury bills, notes, bonds, and Treasury inflation-protected securities (TIPS) to other federal government agencies, individuals, businesses, state and local governments, as well as people, businesses, and governments from other countries. Savings bonds are sold to individuals, corporations, associations, public and private organizations, fiduciaries,* and other entities.

Here is how Treasury securities—such as savings bonds—generally work. People lend money to the government so it can pay its bills. Over time, the government gives that money, plus a bit extra, back to those people as payment for using the borrowed money. That extra money is “interest.”

This is how the U.S. system of debt works:

The U.S. Treasury issues or creates the debt.

The Bureau of the Fiscal Service manages the government’s debt. Thatmeans it keeps records, takes care of selling the debt, and handles payingback people who loaned the government money.

The U.S. Treasury and the Bureau of the Fiscal Service do not decide howthe money is spent. The legislative branch of government (Congress)decides how the money is spent.

*fiduciaries: people who make financial decisions for others



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There is a maximum amount of debt the government can have. This isknown as the “debt ceiling.” To raise that amount, the U.S. Treasury mustget Congress to approve a new and higher limit.

17 Which quote supports the central ideas that debt is a broad concept and that money can be given and taken?

A “Debt is money one person, organization, or government owes to another person, organization, or government.”

B “Credit cards are also a form of debt.”

C “There are different kinds of taxes.”

D “When the government borrows money, it doesn’t go to the bank and apply for a loan.”

18 What causes people to go into debt?

A There are loans that people want to offer that others want to borrow.

B There are things that people want to make that need supplies to create.

C There are gifts that people want to give others that cost very little money.

D There are things that people want that cost more money than they have.



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19 How does the role of the government as a business affect its debts?

A The responsibility of providing essential services means that there is a strong need for additional money.

B The responsibility of providing nonessential services must be carefully evaluated before spending money.

C Just like a business, the government must cut jobs and spending in order to stay within its yearly budget.

D Unlike a business, the government cannot cut jobs unless tax collection does not provide its yearly budget.

20 Which quote supports the author’s point of view about government overspending?

A “The U.S. government is just like a business.”

B “It also needs money to buy supplies and equipment.”

C “The government’s main source of money is the taxes it collects from individuals and businesses.”

D “The amount of money the government spends to pay for the services it provides is often more than the taxes it collects.”

21 What does the phrase “issues debt” mean in paragraph 8?

A The government applies for a loan from large banks to fund its projects.

B The government refuses loans to other banking industries in order to pay its bills.

C The government sells bonds and securities.

D The government reduces its spending on projects.



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22 What does the word marketable mean as used in paragraph 8?

A able to be lost

B able to be traded

C able to be sold

D able to be given

23 Which quote supports the idea that the government has no true limit to the amount of money it can borrow?

A “However, the amount of money the government spends to pay for the services it provides is often more than the taxes it collects.”

B “Over time, the government gives that money, plus a bit extra, back to those people as payment for using the borrowed money.”

C “That means it keeps records, takes care of selling the debt, and handles paying back people who loaned the government money.”

D “To raise that amount, the U.S. Treasury must get Congress to approve a new and higher limit.”

24 How do savings bonds benefit individuals?

A The government borrows money from the individual and repays it with interest.

B The government issues a loan to a business, and the business helps the individual.

C The individual borrows money from the government and repays it with interest.

D The individual issues a loan to a business, and the business helps the government.

The Truth About a Bird’s Eye View · 2020-02-19 · eye has its own lens, rods, and cones, and...

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