Energy is something that makes things work or causes changes. Light, heat, sound and electricity are forms of energy. Here is an introduction to them.
Light comes from the sun. It also comes from flashlights, candles and streetlights. Light is important because it lets us see things. It can pass through clear objects, such as clear glass or clear plastic. But it cannot pass through objects that are not clear. Sunglasses will stop some light and protect our eyes.
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Heat comes from many things. The sun makes the earth's land, water and air warm. （A）We get heat from burning things like wood or coal. Heat is an important energy for us. Heat makes our body and our homes warm in winter. We also use heat to cook.
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Sound is a kind of energy that you can hear. Sound is made when something vibrates（振动）. When you talk or sing, put your hand on the side of your neck. Then you will feel your neck vibrating. When you hit a drum, the drum and the air around it vibrate. When the vibrating air reaches your ears, you hear the sound. There are loud sounds and soft sounds. When you shout, you make a loud sound. When you speak very quietly, you make a soft sound. All sound has pitch（音高）. A drum is an instrument with a low pitch. A bell is an instrument with a high pitch.
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Electricity is made by burning fuel（燃料）. Electricity moves through wires into buildings and homes. It gives many things power to work. Electricity makes lamps, computers, fridges, TVs and many machines work. Electricity makes streetlights shine. Electricity can run through water, so never use it near water.
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