This document discusses energy, tools, machines, and how they have changed over time. It explains that machines make work easier and are either simple machines like levers, wheels, and screws or complex machines that combine two or more simple machines. Simple machines include the lever, wheel, screw, wedge, and inclined plane. Complex machines mentioned are the wheelbarrow, crane, escalator, and scissors. The document also discusses how computers are machines that allow us to work, listen to music, and play games when connected to the internet. It provides examples of how tractors and washing machines have replaced horses and washing by hand. Finally, it outlines different types of energy like human, electrical, solar, and wind energy that