Today we use all kinds of big machines like cranes, bulldozers, and excavators to build things. But how did the ancient Egyptians build their massive pyramids without any of these machines? Experts think they used simple machines like wedges, levers, and ramps. And the big modern machines we use today all have simple machines in them! We learn about backhoes, machines with treads, hydraulic systems, mining excavators, electric powered machinery, electric motors, simple machines (levers, incline planes, screws, wedges, and pulleys), and simple machines in our bodies (elbows, knees, and teeth).