4. COMMUNITIES BEGAN TO USE ENERGY (I)

 The sun and wood gave man energy for a long time. It was only about 5,000 years ago that people started using other sources. People began using the wind to move from one place to another. They built boats with sails that captured the wind. They could travel to new places. Wind was the first energy source used for transportation.

About 2,500 years ago, people began using windmills and water wheels to grind grain. Later, these simple machines were used to pump water and run sawmills.

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