science3.doc

Magnet
This small
Flat horseshoe
Is sold for
A toy: we are
Told that it
Will pick up pins
And it does, time
After time; later
It lies about,
Getting its red
Paint chipped, being
Offered pins less
Often, until at
Last we leave it
Alone: then
It leads its own
Life, trading
Secrets with
The North Pole,
Reading
Invisible messages
From the sun.
You can use a lever to open a can of paint. Leverage，lever
First you put a metal stick under the lid. Then you press down on the stick. The lid will lift up.

A ramp can help you move things to a higher place.

The Earth has a magnetic field. It has two poles, a north pole and a south pole.

When you snap a string, it vibrates.

When you speak, your vocal cords vibrate.
Volume describes the loudness of a sound.
When you yell, you make big vibrations in your throat. When you whisper, you make smaller vibrations.
cat’s meow
A lion’s roar can be so loud that you can hear it up to 6 miles away.

Sounds can be high, low, or in between. Pitch describes how high or low a sound is.
The faster the vibrations, the higher the pitch.

A male elephant can weigh 16,500 pounds!
That is as much as 275 second graders!
估计是学生

In a baseball game, you would hit a homerun every time. 指月球上 估计是全垒打
%home 'run noun [C] (INFORMAL homer) US
a point scored in baseball by hitting the ball so far that you have time to run all the way round the four corners of the playing field before it is returned
Bats use echolocation to move around and catch food.

The sound vibrations from the squeak move through the air and hit a moth. The vibrations bounce off the moth and come back to the bat. Then the bat swoops down and catches the moth for a meal.

Dolphins make clicking noises to help find food.

These workers explore what happens to dummies, or big dolls, in a car crash.
Grade 2 完结

These are the great-greatgreat-
great-grandparents
of the Sierra Nevada

their many scars tell
of the storms and fires
they have survived

every year without fail
their huge trunks
add another ring

thick in a wet year
with plentiful rains—
thin in a dry one

it takes my whole
family holding hands
for us to give a hug

to the tallest
and oldest tree
in this grove

Scientists group environments with similar traits into
biomes (BIGH•ohmz).
A biome is an area of land or water that has certain kinds of living and nonliving things. Deserts, forests, and grasslands are examples of biomes.

Each biome has a certain kind of climate (KLIGH•mit).
天气英文发音的确是写成Meht,但有声发音却是Mit

Humus（HYEW•muhs） is broken-down plant and animal material.
Humus adds nutrients to the soil. It soaks up rainwater and keeps the ground moist.

These parts help plants live, grow, and reproduce.
Reproduce means to make new plants like themselves.

A young kangaroo develops in its mother’s pouch. There it stays safe.

A porcupine’s sharp quills help it stay safe from other animals. 豪猪
豪猪怎么长得跟刺猬一样啊。。。

Cactuses grow well in Southern California.
Cacti 也是仙人掌的复数，都认不出Cactuses来了。。。

A wave of heat blasts your body.
You take a deep breath and dry air stings your nose.
Dust from the sandy ground covers your shoes.
You are in the Sonoran Desert.

The soil in a desert is mostly sand.
There is little humus to soak up rain water.
Rain water trickles down through the desert sand.

Succulent 肉质植物
没想到芦荟的花是这样的。。。

Rattlesnakes and coyotes, among others, are nocturnal
(nahk•TURN•uhl). Nocturnal means they sleep during the day and come out at night.

Their body coverings blend in with their environment.
Blending in is an adaptation called camouflage (KAM•uh•flahzh).
Camouflage helps animals stay safe.

Miles of green grass stretch out before you.
Wildflowers bloom.
The air is warm against your skin.
Grasshoppers jump.
Agreen snake slithers. Suddenly, the wind blows and thousands of blades of grass make a quiet swishing sound. 蜿蜒而行； 沙沙声
You are in the grasslands of North America.

Grass is both a hiding place and a shelter from the wind and cold.
Grass holds down soil that would otherwise blow away in the wind.

Temperate grasslands are one type. Temperate means the environment has a mild climate and four seasons. Temperate grasslands have soil that is rich in humus. 估计是温带草原
Humus helps keep the soil moist. It also supplies nutrients for plants to grow.

Tropical grasslands are the second type of grasslands. Tropical means the environment is near the equator and is warm all year round. Tropical
grasslands have a rainy season and a dry season. 估计是热带草原

When a fire burns, everything above ground is destroyed. Down below, the roots survive. They hold on to their moisture and nutrients.
After a fire, new stalks can grow from the roots.

Its bark is fire resistant, making it well adapted to survive grassland fires.
Baobab trees have bark that resists fire.

Cheetahs can catch prey by running fast.

Grasslands, known as pampas, are common in South America.

This camouflage helps them hide from predators like foxes and hawks that eat the birds or their eggs. 捕食者

The tinamous are hard to see, but their shiny green, turquoise, and purple eggs really stand out. 绿松石 一种鸟蛋的颜色很特殊

It is dark and damp.
Tall trees surround you.
Raindrops drip from overhead.
The hot, moist air feels heavy around you.
Insects buzz. Birds sing.
You are in the Amazon Rain Forest.

A tropical rain forest is a forest biome found near the equator.
A temperate forest is a forest biome found in North America, Europe, and Asia.

Although tall, many of these trees have shallow roots. Buttresses help support their tall size. Buttresses are special root structures that spread out from the trunk.
只查到墙撑，但能意会在根系中的结构功能
Many kinds of animals swing, swoop, dart, and jump in the canopy.
反正都是猛扑，猛冲之类的意思

Coniferous tree 松柏类针叶树

Leaves on deciduous trees change from green to yellow, orange, and red in the fall. They fall off, then grow back in spring.
落叶木
Evergreen trees 常绿木

The tall trees of the temperate forest are deciduous (di•SI•juh•wuhs) or coniferous (coh•NI•fuh•ruhs).
Coniferous trees make cones instead of flowers. Coniferous trees are often called evergreens. Their thin, needle-like leaves are tough and waxy.

This adaptation is called mimicry (MI•mi•kree). Mimicry is when one living thing imitates another living thing in color or shape.

Some animals hibernate (HIGH•buhr•nayt).
Hibernate means to go into a deep sleep that lasts through the winter.
The animals live off energy stored in their bodies.

You’ve reached Denali National Park.
The air is so cold it burns your lungs.
A biting-cold wind whips across your face. T
he ground is frozen and hard beneath your feet.
This is the arctic tundra.
The arctic tundra is the cold biome above the Arctic Circle.

Permafrost is soil that is always frozen. The land becomes soggy with pools of water. 湿润的
As temperatures rise, the top few inches of soil thaw. 解冻

Many arctic plants grow close together in tight clumps that look like cushions. Growing together is an adaptation that protects plants from wind and freezing temperatures. Plants that grow this way are called cushion plants. 一簇 聚在一起看起来像垫子所以叫垫子植物？中文怎么称呼？

Polar bears, musk oxen, and many other arctic animals have thick fur coats. They also have a thick layer of blubber. Blubber is fat.

估计是牦牛哥哥

To migrate (MIGH•grayt) means to move to another place.
Animals migrate when their home environment can no longer meet their needs.