A simple machine is a tool most often used by a person to make a job easier or more efficient. A machine with one working part is classified as simple, whereas a tool with multiple parts working together or in sequence is considered a compound machine. Children can make many simple machines for fun or to demonstrate the different uses of simple machines. The six types of simple machines are pulleys, levers, screws, inclined planes, wheels and axles and edges.
Build a suspension cable by tying an empty soda bottles to a broom stick using different types of material to secure the bottles, including dental floss, yarn, rope, or any other material available. Fill the soda bottles with water to see which material supports the most weight. Do this experiment outside, in case one bottle breaks and spills. Children should be able to see this experiment's connection to the world any time they cross a suspension bridge or see other types of suspension cables in use.
Build a Lever
Build a simple lever using a ruler, a pencil, tape and two paper cups. By taping the pencil to the table and laying the ruler over it, you make a lever. See how the lever works by placing paper cups on the ruler, taping them down if they slide and putting weights in each cup. Children can see how different weights affect what pulls the lever up and down, and how moving the ruler to have different lengths on either side of the pencil also affects how the simple machine distributes weight.
Children themselves can easily become simple machines by forming their hands into a wedge. Have a child put his palms together as though praying. Fingertips first, instruct the child to push his hands between objects such as a stack of books, a stack of folded towels, or even another person's hands. The wedge created by his own hands should easily push apart the objects just as a wedge made from a block of wood or other material would do.
Make a Pulley
Make a simple pulley machine with a wire coat hanger, wooden spool, string, cup hook screwed into a board or a tension rod, and a book. With an adult's help, cut the coat hanger's bottom rung in half and thread the wires through the wooden spool so the spool will not fall off. Hang the coat hanger from a secured tension rod or a secured cup hook. Loop string around the spool and attach one end of the string to a book by tying it around the book. By pulling the loose end of the string, children can see how the pulley works to lift the book.