2. Levers can make it easier for people to lift heavy objects or open things. The object being moved by a simple machine such as a lever is called a load. You would use less energy using a lever than if you simply tried to lift a rock. A wheelbarrow and seesaw are examples of levers.

3. There are two types of pulleys a movable pulley and a fixed pulley. A single fixed pulley makes work easier by changing the direction of the effort force. When pulleys are used they can decrease the effort force needed to lift a load.

4. A wedge changes a downward or forward force into a sideways force. A wedge is two inclined planes back to back. The blade of an ax is a wedge with a sharp edge. A wedge is a moving inclined plane.

5. Movers use inclined planes to slide heavy objects in and out of their trucks. Inclined planes are also used to make it easier for handicapped people to get around. An inclined plane is a simple machine that only has one part.

6. A screw is an inclined plane twisted into a spiral. When a screw is turned, It moves forward. You have to keep turning a screw for it to move a short distance. You need only a small effort force to turn a screw.

7. When you turn a doorknob, you are using a wheel and axle. A Ferris wheel is a wheel and axle. The wheel and axle has 2 parts, a wheel and the bar that passes through the center of the wheel. A screwdriver is a wheel and axle.