<p class="ql-block"><b>1-Review Sound And Echo </b></p><p class="ql-block">Human and animals use sound to recognize and communicate with each other. Besides sound, there are other ways to communicate such as body lauguage and sign language.</p><p class="ql-block">All sound is caused by the vibration.Touch your throat to feel the vibration. When you shout out loud, You can feel the vibration of your throat.</p><p class="ql-block">In fact, Sound is a form of energy, just like electricity and light. Sound is made when air molecules vibrate and move in the pattern called waves. Think of when you clap your hands or slam the door shut. That action produces sound waves, which travel to your ears and then to your brain, which says “I recognize that sound”</p><p class="ql-block">when the sound is lower, the sound wave is short. But when the sound is loud, the sound wave is long. Come and make your sound to I-Pad. It can show you the sound wave.</p> <p class="ql-block">Do you remember what is an echo?</p><p class="ql-block">An echo is a sound that is repeated, because the sound waves are reflected back. Sound waves can bounce off smooth, hard objects , just as the rubber ball bounces off the ground. Although the direction of the sound changes, the echo sounds the same as the original sound. Echoes can be heard in small spaces with hard walls, like well, or where there are lots of hard surface all around like cave, mountains. But sounds are not always reflected. If they meet a soft surface, such as a cushion, the sound will be absorbed and will not bounce back.</p><p class="ql-block">Maybe you will wonder why we can’t hear the echo when we sound at the wall. Let’s look at the picture. the Original sound waves travel through air, If there is a block in front of you, sound waves will be reflected back to your ears which is called reflected sound. When the reflected sound waves are later than the original sound waves, echo will come out. That means you and the sound reflecting surface must be far away enough.</p> <p class="ql-block"><b>About Noise</b></p><p class="ql-block">We use sound to communicate with each other. But sound becomes undesirable When it disturbs the normal activities such as working, sleeping. It is called as noise. When there is a lot of noise in the environment, it is termed as noise pollution. </p><p class="ql-block">We use the unit Decibel to measure the sound. That is a device called decibel meter. If the sound is above 85 DB, it is called a noise which means it is harmful for our ears. Stay in a noisy environment for long time, the ears can’t work any more, the guy will be deaf.</p><p class="ql-block"><br></p> <p class="ql-block"><b>2-All about Season </b></p><p class="ql-block">M: honey, what is the weather like today?</p><p class="ql-block">B: a little cool and sunny</p><p class="ql-block">M: that’s right. The Weather always changes during the year. These changes are called seasons. Each season brings changes that are very important for plants and animals that live in different places of the world.</p><p class="ql-block">So how many seasons are there in a year? could you tell me what they are one by one?</p><p class="ql-block">Spring- Summer-Autumn/Fall- Winter</p><p class="ql-block">M: In the north and south there are four seasons in a year. But at the north and South Pole there are only two seasons. When it is summer in the north, it is winter in the south. The weather in north and south are just the opposite.</p><p class="ql-block"><b>Spring</b>- the day and night are the same length. The weather gets warmer and sunnier. Tree and plants start to grow. Many animals have their babies in spring. It is a good season to go hiking. Many people go outside to relax themselves.</p><p class="ql-block"><b>Summer</b>- the day time becomes longer and the night becomes shorter than before. it is the warmest and sunniest time of a year. Fruit grows on trees and plants. Young animals grow bigger and stronger. People will spend lots of time on the beaches.</p><p class="ql-block"><b>Autumn</b>- the day and the night are the same length again. During autumn, the leaves change color and fall from trees. Some animals collect food before winter comes.</p><p class="ql-block"><b>Winter</b>- the day are shorter and the night are longer. The weather is colder and in some places there is of snow. Plants and trees stop growing. Some animals find places to hide and sleep. This is called hibernation.</p> <p class="ql-block"><b>3-Where do we live</b></p><p class="ql-block">M: honey, how does our Earth looks like? A blue ball, because ocean covers 70% of it. </p><p class="ql-block">And the left of our earth is the land. The land is divided into several continents.</p><p class="ql-block">Look at the picture, it is a picture of the earth. The light-yellow part is the ocean, these are the continents. Let’s count how many continents the earth have. M: seven! There are seven continents on the earth. And we live one Asia, the biggest continent on the earth. </p><p class="ql-block">The middle line is the Equator. Let’s take a look where are the Amazon Rain forest and Africa savanna</p><p class="ql-block">We live in the south part of our country, near the Tropic of Cancer. Our climate is not cold in winter.</p> <p class="ql-block">the salt water that covers most of the earth's surface and surrounds its continents and islands.</p><p class="ql-block">What's the difference between an ocean and a sea ?</p><p class="ql-block"><b>Seas</b> are smaller and less deeper than oceans. Sea are usually located where the land and ocean meet.</p><p class="ql-block">A sea is part of an ocean that is partially enclosed by areas of land.</p><p class="ql-block"><b>Ocean</b> is a vast and continuous frame of salt water that covers about 70% of the global surface.</p> <p class="ql-block"><b>All about bear</b></p><p class="ql-block">Bears are large, powerful mammals related to dogs and raccoons. The biggest bears are the world's largest animals that live on land and eat meat.</p><p class="ql-block">There are several species, or types, of bear. They are the polar bear, the brown bear, the black bear, the Asiatic black bear, the sun bear, the spectacled bear, and the sloth bear. The brown bear is commonly called the grizzly bear in North America. Most scientists also consider the giant panda to be a member of the bear family.</p><p class="ql-block"><b>Where Bears Live</b></p><p class="ql-block">Bears are found in the Americas, Europe, and Asia. They are often found in mountainous areas and forests. The black bear lives in North America. The brown bear is found in North America, Europe, and Asia. The Asiatic black bear and the sloth bear live in parts of Asia. The world’s far northern regions called the Arctic are home to the polar bear.</p><p class="ql-block">Most bears live in northern regions with a mild or cold climate. However, the spectacled bear is found in the Andes Mountains of South America. The sloth bear of India and Sri Lanka lives in hot or warm regions.</p><p class="ql-block"><b>Physical Features</b></p><p class="ql-block">Bears range in height from about 3 to 10 feet (1 to 3 meters). The sun bear is the smallest species. A kind of Alaskan brown bear called the Kodiak bear is the largest bear. It may weigh 1,720 pounds (780 kilograms). Some polar bears are almost that big.</p><p class="ql-block">Most bears are mainly brown, red-brown, or black. Some have white markings on the chest or face. The type called the black bear is sometimes actually brown, blue-gray, or even white. The polar bear's white fur helps it blend in with the Arctic ice and snow.</p><p class="ql-block">Bears have broad heads, large bodies, and short legs and tails. They have poor eyesight but an excellent sense of smell. Most kinds are good at climbing trees and at swimming</p><p class="ql-block"><b>Behavior</b></p><p class="ql-block">Bears are carnivores, or meat eaters. For example, the polar bear eats seals, walrus, and fish. However, other bears eat a large amount of plants as well as animals. They may eat roots, seeds, berries, and nuts, plus insects, fish, and deer.</p><p class="ql-block">In the autumn most bears eat a lot to put on extra fat. They then sleep through most of the winter. This is similar to a very deep resting state called hibernation. But bears are not true hibernators. Their body temperature, heartbeat rate, and breathing rate do not drop much lower than normal.</p><p class="ql-block"><b>Reproduction</b></p><p class="ql-block">Adult bears tend to live alone except during the mating season. A female bear gives birth to one to four cubs, or babies, at a time. At first the cubs are tiny, hairless, and helpless. They drink their mother’s milk for about two months. The cubs stay with their mother for 18 months or more.</p>