Levers and pulleys are two simple machines that make our lives easier. These basic machines allow us to move, lift and build things using less effort. In our everyday life, we use levers and pulleys to reduce the strength and mechanical force required to get jobs done. Sports equipment, cranes, elevators, tools, playground equipment and even clotheslines are examples of how our lives are easier because of the use of levers and pulleys. Hands-on projects designed for fifth graders can help them understand the concepts of levers and pulleys.
A Simple Lever
When learning about levers, students can create a simple lever to understand the three parts of a lever: the fulcrum, the weight arm and the force arm. The fulcrum supports the lever. For this project, a juice can or other similar can will serve as the fulcrum. Place a board on the can and then place four books on one end. The length of the board from the can to the books is the weight arm. Adjust the board so that the force arm (the opposite end of the board) is shorter than the weight arm. Stack books one at a time on the force arm and record how many books it takes to lift the weight arm. Have the students change the length of the force arm and record whether the weight needed to move the four books changed. The students will learn that adjusting the weight arm and force arm affects the weight required to lift the four books.
A Simple Pulley
Create a simple pulley using two thread spools, two pencils and 40 feet of string. Insert the pencils through the centre of the thread spools. Tie the two ends of the string together and wrap the string around the two spools. Have students hold the ends of the pencils to allow the spools to turn freely. Ask another to student attach a written message to one end of the string with a paper clip. When the student pulls the string, the message will travel to the other side, demonstrating how a pulley can move an object.
The Power of a Lever
Use a hammer to pound several nails into a piece of wood, leaving at least one third of the nail out of the wood. Have the students try to remove the nails using their hands and fingers only. Supply them with a hammer and explain how the claw end of the hammer acts as a lever that generates the power needed to remove the nail from the wood.
To demonstrate how levers and pulleys are commonly used in a student's daily life, have the class create a chart logging how many of theses simple machines they find in a day. Students can go on a scavenger hunt in the playground, in the classroom or at home to find objects to examine and determine whether they work with levers or pulleys. The students can then record the item and how many levers or pulleys they find on it. For example, a bicycle's handles, gear levers and brake pedals use levers and pulleys to operate.