There are six types of simple machines: levers, inclined planes, wheels and axles, screws, wedges and pulleys. According to Todd Kranz from the University of Houston: “Simple machines are tools to make work easier. They have few or no moving parts. These machines use energy to work.” Show students how to create some basic simple machines in class and challenge them to create more elaborate ones at home as a science project.
An inclined plane has a flat surface with one end higher than the other. Examples of inclined planes include ramps and slides. Materials include large books, small wooden boards measuring 3 inches wide by 12 inches long, small plastic bags with 1 cup of rice inside each, rulers and rubber bands.
Put students in groups of three or four. Tell them to place three books in a pile. Have them take the board and lean it against the books to make an inclined plane. Ask them to tie the rubber band around the bag and lift the rice to the top of the book stack. Tell students to measure the length of the rubber band when the bag reaches the top of the books. Place the bag at the bottom of the plane and pull the rubber band so the bag slides up along the plane. Have students measure the length of the rubber band when the bag is at the top of the books. Ask students when the rubber band was longest. Ask them how the simple machine of the inclined plane made the work easier. Brainstorm practical examples for the use of an inclined plane.
Making a Toy Car
A toy car uses the simple machine of a wheel and an axle. Inform students that they are going to make a car to demonstrate how a wheel and axle simple machine makes work easier. Materials include empty 1 quart cardboard milk cartons, scissors, long smooth boards, thick books, coloured pencils and large thread spools.
Put students in groups of four. Supply each group with materials. Tell them to cut the milk carton in half. This make two car bodies. Place the board against a pile of books. Place the car body on top. Ask students why the car is stationary. Have them make two holes on each side of the car in the front and back with the scissors. Slide the pencils through the holes. Put the spools on the pencils to make wheels. Place the car at the top of the ramp and let it go. Ask students why the car moves. Lead them to see that the wheel and axle allow the car to go down the ramp by reducing the friction between the car and the ground.
Making a Stationary Pulley
Use this activity after students are familiar with pulleys and how they work. A pulley helps move things up, down or across. Examples are cranes, flagpoles and curtain rods. Allow each student to work individually on this activity. Tell students they are going to make a flag raiser. Materials include a pencil, a large thread spool, scissors, ruler, string, 4 inch by 6 inch sheets of paper, markers and masking tape.
Give each student a sheet of paper and markers and tell them to design a flag. Demonstrate how to make a pulley and then allow students to make their own. Put the pencil through the spool. Tie the string to form a loop and tape a sheet of paper to it. Loop the string over the spool. Ask a student to hold the pulley by the pencil. Pull the string down and watch the flag rise. Ask students about the direction that you pulled the string and the direction of the flag. You want them to understand that the flag moves in the opposite direction of the pull. Tell students to create their own pulleys and write a paragraph about how a pulley works. Ask them to include a diagram of the pulley.