跟美国学生同步学科学(彩色英文版 Grade 6)(txt+pdf+epub+mobi电子书下载)

作者：(加) 韦恩·艾弗里特

出版社：天津人民出版社

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跟美国学生同步学科学(彩色英文版 Grade 6)试读：

The king penguin is the world' s second largest penguin, reaching over a metre in height and weighing up to 16 kilograms. These large penguins are very strong swimmers and can easily reach depths of over 200 metres! The king penguin looks quite similar to the emperor penguin, except it is a little smaller. Its head, neck, tail, and wings are all black. And like all penguins, it has bright orange patches on its ears as well as several layers of waterproof, down feathers that act as insulation. Additionally, it has a special gland for filtering salt so that it can drink salt water.

The diet of the king penguin consists mostly of small fish, squid, krill, and shellfish. They breed in November or December. After the egg is laid, the male takes care of it, while the female goes hunting in the sea to fatten up. She returns to the egg after about 3 weeks, and takes care of it while the male ventures out to sea. When the baby penguin hatches out of the egg, both parents take turns taking care of it. King penguin chicks rely on their parents to give them regurgitated food for about a year.

King penguins are common and their population is increasing. Scientists estimate their population to be about 2.25 million.Word List

insulation: material that is used for keeping warm

breed: to have babies

regurgitated: eaten and then brought up for babies to eatYou Practice

I. Answer the following questions.

1) What do king penguins look like?

2) What do king penguins eat?

3) What is special about king penguins?

4) What happens after king penguin eggs are laid?

5) What happens after king penguin chicks are born?

II.Word power—Use these words from the reading in sentences of your own.

1) feathers ______________________________________________

2) insulation _____________________________________________

3) waterproof ____________________________________________

4) shellfish ______________________________________________

5) regurgitated ___________________________________________

III. True / False / Not Given—Write T if the sentence is true, F if it is not true, or NG if there is no information about the sentence.

____ 1) King penguins are the largest kind of penguin.

____ 2) Only female penguins take care of their chicks.

____ 3) King penguins are endangered.

____ 4) King penguin chicks feed themselves.

____ 5) King penguins have black wings.02Looking Closely at the World

Scientists are always trying to solve the mysteries of the universe. These people use their various skills to investigate what, why, where, and how things happen. Two of the most important tools a scientist has are observation and experimentation.

Science always begins with observation. Careful observation always leads to questions. Then a hypothesis can be formed. However, a hypothesis is only useful if it can be tested.

The best way to test a hypothesis is to design an experiment. Each experiment is designed to answer one question only — is the hypothesis true or false? In nature, there are often too many variables to know why something happened. However, a scientist can limit the number of variables.

Although experiments are important, they aren' t always practical. An astronomer can' t travel across space, but with observation, he or she can still learn a lot about stars. For example, experiments on Earth have shown that when elements are burned, each one gives off a very specific colour. By observing the colours of stars, astronomers can tell which chemical elements the star contains.

Certain types of science use observation much more than experimentation. Archaeology, paleontology, and astronomy rely on observing the world, and then drawing conclusions based on the evidence.Word List

investigate: try to find answers

hypothesis: an idea about why and how things happen

variables: possible reasons for things happeningYou Practice

I. Answer the following questions.

1) Why are observation and experimentation both important?

2) Why can experiments often give clearer answers than nature?

3) Why is observation so important for an astronomer?

4) What is a hypothesis?

5) Why is it not always possible to conduct experiments?

II. Word power—Use these words from the reading in sentences of your own.

1) hypothesis ____________________________________________

2) observation ___________________________________________

3) variables ______________________________________________

4) evidence ______________________________________________

5) investigate ____________________________________________

III. True / False / Not Given—Write W if the sentence is true, F if it is not true, or NG if there is no information about this sentence.

____ 1) Science begins with experimentation.

____ 2) A hypothesis tries to answer many questions.

____ 3) A hypothesis must be tested to be useful.

____ 4) In order to make observations, astronomers must travel through space.

____ 5) Part of a scientist' s job is to limit the number of variables in an experiment.03On the Rise

If you know anything about baking bread, you know that in order to make it rise, you need yeast. It looks like other powdery ingredients, but it is still alive. When it is dry, it is dormant, but when it is moist and warm, it comes to life.

Yeast is similar to plants, but it can' t make its own food the way plants do. Instead, it feeds on sugar. As yeast breaks down the sugar to make energy, a chemical reaction called fermentation takes place. This creates alcohol and carbon dioxide as waste. The carbon dioxide appears as little bubbles of gas. These bubbles are what cause bread dough to rise and baked bread to have its light, spongy texture.Experiment

Materials: two packets of yeast, two plastic bottles, two balloons, warm water, granulated sugar, a tablespoon, a funnel.

• Pour a cup of very warm water into each bottle. Place a funnel over the mouth of bottle 1 and add two tablespoons of sugar. Place the cap on the bottle and shake it until the sugar dissolves.

• Open the bottle and put the funnel over the mouth again. Add the yeast and replace the cap. Swirl the mixture around in the bottle until the yeast dissolves. The water should be cloudy. Follow the same procedure to add yeast—but not sugar—to bottle 2, the control bottle.

• Open each bottle and slide the end of a balloon over the bottle' s mouth. Make sure that the balloons create a tight seal.

• Put the bottles in a warm place, like a sunny windowsill. After about 20 minutes, you will notice that balloon 1 has inflated. It trapped the carbon dioxide that the yeast produced during fermentation. Balloon 2 will not have inflated, because yeast does not ferment and produce carbon dioxide without sugars to feed on.Word List

dormant: not active

swirl: move around in a circle

inflated: filled with airYou Practice

I. Answer the following questions.

1) How can we make yeast come to life?

2) What is the main difference between yeast and plants?

3) In the experiment, why does balloon 2 not inflate?

4) What is fermentation?

5) Do you like this experiment? Why or why not?

II. Word power—Use these words from the reading in sentences of your own.

1) yeast _________________________________________________

2) inflate ________________________________________________

3) dormant ______________________________________________

4) cloudy _______________________________________________

5) rise __________________________________________________

III. True / False / Not Given—Write T if the sentence is true, F if it is not true, or NG if there is no information about this sentence.

____ 1) Yeast feeds on sugar.

____ 2) Most bread contains yeast.

____ 3) It is possible to make bread without yeast.

____ 4) Yeast is a kind of plant.

____ 5) In the experiment, both bottles contain the same ingredients.04A Sticky Lesson

Millions of years ago, long before the city of Los Angeles existed, the area was covered by the Pacific Ocean. Over time, it turned from sea to land. Oil came to the surface through cracks in the ground and pooled in low-lying areas, which are today known as the La Brea Tar Pits.

In warm periods, the oil that came from the ground became sticky and the surface became covered with leaves, dust, and even water. When animals came to drink, they became trapped. Predators that preyed on the trapped animals often became trapped themselves. This sticky area was perfect for fossilizing and preserving the remains of these animals.

Now the La Brea Tar Pits are one of the best places for excavating fossils. More than 3 million fossils have been found there since the early 1900s. There are some really big fossils, like those from animals like mammoths, saber-toothed tigers, and short-faced bears. However, fossils of plants, insects, and smaller animals are also valuable to paleontologists.

Microfossils help scientists form a picture of what life was like in the area around Los Angeles 40000 years ago. For example, by analyzing these fossils, scientists learned that the climate was moister and cooler than today, but not so much different.

To find out how old fossils are, scientists use a process called radiometric dating. Living things contain carbon. A small portion of this carbon is called carbon 14, which is unstable. It takes 5730 years for half of the carbon 14 to become stable, then the same amount of time for the remaining half to become stable, and so on. So measuring the amount of unstable carbon 14 remaining in a fossil allows scientists to accurately

date it. By doing this they found that most fossils in the La Brea Tar Pits were between 8000 and 38000 years old.Word List

excavating: digging things up

paleontologists: scientists who study life from the past

microfossils: very small fossilsYou Practice

I.Bythenumbers—Whatdothesenumbersmeaninthereading?

1) 3 million _____________________________________________

2) 40000 ________________________________________________

3) carbon 14 _____________________________________________

4) 5730 _________________________________________________

5) 8000 to 38000 _________________________________________

II. Answer the following questions.

1) Where are the La Brea Tar Pits?

2) How did so many animals become trapped at La Brea Tar Pits?

3) What kinds of fossils have been found at La Brea Tar Pits?

4) How is carbon 14 useful?

5) What was the weather like at La Brea Tar Pits 40000 years ago?

III. True / False / Not Given—Write T if the sentence is true, F if it is not true, or NG if there is no information about this sentence.

____ 1) The La Brea Tar Pits existed when dinosaurs roamed the Earth.

____ 2) Small fossils can be very important.

____ 3) There are not many fossils remaining at La Brea Tar Pits.

____ 4) Radiometric dating cannot be used for fossils that are millions of years old.

____ 5) Los Angeles has existed for about 38000 years.05Review(Lessons 1-4)

I. Fill in the blanks—Complete the following sentences with words from the readings.

1) A name for fossils that are very small is m _ _ _ _ _ _ _ _ _ _ _.

2) That volcano is not active. It is d _ _ _ _ _ _.

3) Sometimes there are too many v _ _ _ _ _ _ _ _ to understand why something happens.

4) Many animals have fur for i _ _ _ _ _ _ _ _ _.

5) Part of a paleontologist' s job is e _ _ _ _ _ _ _ _ _.

II. Answer the following questions.

1) What are some things you have that need to be inflated?

2) What are some animals that have an increasing population?

3) In a good experiment, how many variables should there be?

4) What are some examples of microfossils?

5) What are some animals that have a lot of insulation?

III.Whatisit?Usingtheclues,tellwhatisbeingdescribed.

1) a sticky, black substance: o _ _

2) it feeds on sugar: y _ _ _ _

3) someone who studies space: a _ _ _ _ _ _ _ _ _

4) flightless birds that live near Antarctica: p _ _ _ _ _ _ _

5) weather over a long period of time: c _ _ _ _ _ _06Pangaea

In the early 1900s, German meteorologist Alfred Wegener was very interested by a scientific mystery. The fossilized remains of some plants had been found on more than one continent. For example, the remains of an extinct, freshwater reptile were discovered by archaeologists in both South America and southern Africa.

Prehistoric reptiles couldn' t swim across oceans and the exact same plant doesn' t evolve in two places at once. How could the fossils of the same animals appear in two places at the same time?

In Wegener' s time, most scientists thought the animals had crossed the oceans on land bridges. However, Wegener wasn' t so sure about this idea.

Wegener noticed that Earth' s continents looked like puzzle pieces. The eastern edge of South America fit perfectly into the western edge of Africa if the continents could be put together. The landscapes also matched up. For example, a mountain range in South America matched perfectly with one in southern Africa.

1n 1915, Wegener published his book The Origin of Continents and Oceans. His hypothesis was that continents move around the planet, an idea he called continental drift. At one time, all the landmasses were joined together in a single supercontinent called Pangaea.

Plants and animals moved freely across Pangaea and when the supercontinent broke up, the fossilized remains ended up on separate continents.

Many scientists thought Wegener' s hypothesis was ridiculous. How could continents move? Wegener didn' t have the answer, but he was sure he was correct.

In the 1950s, scientific equipment led to the theory of plate tectonics. Suddenly, many scientists began to accept Wegener' s theory. Today it is accepted as fact, and Wegener is regarded as one of the greatest scientists ever.Word List

meteorologist: someone who studies the science of weather

organisms: living things

land bridges: pieces of land that connect two larger landmasses

continental drift: the theory that continents move

plate tectonics: the theory that the Earth' s crust is divided into sections, called plates, that move around the planetYou Practice

I. Answer the following questions.

1) What scientific mystery was Alfred Wegener interested in?

2) What is Pangaea?

3) What important detail did Wegener discover about the continents?

4) Why do you think many scientists thought Wegener' s hypothesis was ridiculous?

5) Why is Wegener now regarded as one of the greatest scientists of all time?

II. Word power—Use these words from the reading in sentences of your own.

1) meteorologist __________________________________________

2) drift _________________________________________________

3) fossilized _____________________________________________

4) evolve _______________________________________________

5) mystery ______________________________________________

III. True / False / Not Given—Write T if the sentence is true, F if it is not true, or NG if there is no information about this sentence.

____ 1) Alfred Wegener lived in Pangaea.

____ 2) At first most scientists agreed with Wegener about continental drift.

____ 3) Wegener discovered many types of plants and animals.

____ 4) Pangaea no longer exists.

____ 5) Wegener was correct about the continents moving.07Jackson' s Chameleon

The Jackson' s chameleon is a typical chameleon, which can be up to 30 centimetres long. They are usually bright green, although females are sometimes dull green or brown. Similar to other chameleons, these chameleons can change colour according to their mood or environment. It may become red or orange when predators are near. They have short necks, long prehensile tails, and eyes that focus independently — giving them 360 degree vision.

The chief dietary item of the Jackson' s chameleon is insects. To catch insects, the Jackson' s chameleon sticks out its long, sticky tongue. This fast moving tongue can reach up to 45 centimetres and can be fully extended in 1/16 of a second. It also feeds on water that falls from leaves.

The Jackson' s chameleon can be found in forested, mountainous parts of Kenya and Tanzania in eastern Africa. They usually stay in trees and only come to the ground in order to mate or lay eggs. Females give birth to 8 to 30 young after a pregnancy of 5 or 6 months. Their lifespan is around 10 years. These reptiles are still common, but many have been illegally sold as exotic pets.Word List

prehensile: able to be used like an arm or leg

exotic: unusualYou Practice

I. By the numbers—What do these numbers mean in the reading?

1) 30 ___________________________________________________

2) 360 __________________________________________________

3) 45 ___________________________________________________

4) 8 to 30 _______________________________________________

5) 10 ___________________________________________________

II. Answer the following questions.

1) What does the Jackson' s chameleon look like?

2) What is special about the Jackson' s chameleon' s eyes?

3) Where can Jackson' s chameleons be found?

4) What do Jackson' s chameleons eat?

5) Where do Jackson' s chameleons spend most of their time?

III. True / False / Not Given—Write T if the sentence is true, F if it is not true, or NG if there is no information about this sentence.

____ 1) The tongue of the Jackson' s chameleon is longer than its body.

____ 2) Male and female Jackson' s chameleons are always the same colour.

____ 3) The tail of the Jackson' s chameleon is very useful.

____ 4) The Jackson' s chameleon is endemic to Africa.

____ 5) The Jackson' s chameleon sometimes eats fruit.08Moving Energy

Thermodynamics is the study of how energy moves through the world. Heat is energy moving from one place to another. When heat adds energy to a substance, the atoms and molecules begin moving more quickly. The amount of thermal energy in a substance determines whether it will be solid, liquid, or gas.

The molecules in solids are packed tightly and move slowly. Heat increases the thermal energy, so the molecules move more quickly and bounce against each other with more force. They need more room to move, so the solid expands and the substance changes to liquid. More heat brings more thermal energy and the substance expands again to become gas. Energy follows the three laws of thermodynamics.

The first law is that energy is neither created nor destroyed. This means there is only so much energy in the universe. It moves around a lot, but the amount never changes. For example, if you drop an ice cube into a cup of coffee, thermal energy moves from the coffee to the ice. Solid turns to liquid — the ice melts.However, at the same time the coffee cools because it lost thermal energy to the ice. This happens on a much bigger scale in the universe.

The second law is entropy. When two substances have different amounts of thermal energy, this law states that energy will move between them until they have equal amounts. Heat always flows toward the substance with less thermal energy.

Finally, the third law states that at absolute zero entropy becomes total. It is at absolute zero that atoms and molecules stop moving. They have no energy because they' re spread evenly through the substance. The colder something is, the less energy it has.Word List

packed: very close together

absolute: complete, total

entropy: randomness

absolute zero: the lowest temperature possibleYou Practice

I. Answer the following questions.

1) What determines whether something is solid, liquid, or gas?

2) What is thermodynamics?

3) Why does dropping an ice cube into a hot cup of coffee make the coffee cooler?

4) Why do molecules stop moving at absolute zero?

5) What happens when hot water is poured on an ice cube? Why?

II. Word power—Use these words from the reading in sentences of your own.

1) substance ______________________________________________

2) packed _______________________________________________

3) energy _______________________________________________

4) absolute ______________________________________________

5) spread ________________________________________________

III. True / False /Not Given—Write T if the sentence is true, F if it is not true, or NG if there is no information about this sentence.

____ 1) The amount of energy in the universe is always changing.

____ 2) Things that are hot have more energy.

____ 3) Energy moves around a lot in the universe.

____ 4) When the temperature drops, energy is destroyed.

____ 5) Absolute zero is too cold for people to survive.

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