Use these free STEM lessons, projects, and activities to teach about simple machines with hands-on science experiments to investigate how levers, pulleys, ramps, screws, and wheel and axle systems offer mechanical advantages that make it easier to perform tasks.

## What Are Simple Machines?

A simple machine is a machine with few or no moving parts that makes it easier to perform a certain type of work. Simple machines do not create energy, which must be conserved. In other words, simple machines do not decrease the amount of work it takes to perform a task. However, they can make the work seem easier by reducing the force required (while increasing distance) or by creating mechanical advantage to increase force (while decreasing distance). Examples of simple machines can be found all around us, from tools we use in our homes to machines used in the everyday world.

A ramp extending from the back of a moving truck to the ground, for example, forms an inclined plane that makes it easier to load heavy items onto the truck. It is important to keep in mind that a simple machine doesn't reduce the amount of work. Work is equal to the force applied to an object multiplied by the distance the object moves (W=f × d). In the moving truck example, the inclined plane reduces the force required to lift heavy objects but increases the distance the object(s) will need to be moved. The simple machine makes loading the items seem easier, but it requires the same amount of work. Bolt cutters have the opposite force/distance tradeoff. You move the handles through a large distance with a small force, and the blades move through a much smaller distance but with a higher force, allowing you to cut through a bolt.

Six common simple machines are: the inclined plane, the lever, the pulley, the screw, the wedge, and the wheel and axle. More complex machines often use one or more simple machines.

These student projects can be used to introduce and explore simple machines:

## Experiment with Six Common Simple Machines

The resources below highlight specific types of simple machines, allowing students to hone in on how these machines are used in everyday products and devices. These resources have been grouped into the following six categories:

At the bottom of this resource, you will find engineering design challenges that make use of combined knowledge of common simple machines, related STEM careers, a list of key vocabulary words, and additional related resources. For students looking for science projects, we have also included a list of independent science and science fair projects.

### Inclined Plane

An inclined plane is a tilted surface or ramp between different heights. An inclined plane can make it easier to move things between elevations, requiring less effort to move to a higher elevation (compared to lifting straight up). The slope of the plane reduces the force needed to move the object to a higher elevation. However, an inclined plane increases the distance between the elevations and thus requires force over a greater distance (the length of the slope).

Many examples of inclined planes in discussions of simple machines focus on easing the task of lifting an object or moving an object to a higher elevation. Students will notice, of course, that an inclined plane also allows the lowering of an object between elevations. A ramp can help slow or control the download movement.

Ramps, stairs, and slides are all examples of inclined planes. Skateboard ramps, for example, allow a skateboarder to get into the air with less effort (and more control) than if transitioning to a trick directly from a flat surface. Similarly, a ramp for a wheelchair makes it easier for the chair to move up and down the distance between elevations.

The following science projects and experiments involve inclined planes:

1. ### 1. Paper Roller Coasters

In the Paper Roller Coasters: Kinetic and Potential Energy lesson, students build roller coasters from paper and experiment to see if they can add a loop to the coaster and have a marble successfully make it from start to finish. The lesson focuses on the shift between potential and kinetic energy as the marble moves along the track, but the undulating shape of a roller coaster track may involve multiple instances of inclined planes. Questions: Why might the entrance to a roller coaster loop involve an inclined plane? In a real roller coaster, what other inclined planes can students identify? Hint: Where does the roller coaster car begin its path? How does it get there?

Paper Roller Coasters - Fun STEM Activity!
2. ### 2. Engineer a Paper Ball Run

In the Paper Ball Run challenge, students are tasked with using limited materials to design a ball run that will take as long as possible for the ball to complete its run. Students can approach the design and function of the ball run — and the "slow the roll" challenge — in myriad ways, but many student ball run designs incorporate inclined planes to both keep the ball in motion and to keep it moving toward the exit point. Inclined planes may be used in a ball run to help reduce the angle of the decline, thus slowing the ball's run. Inclined planes could also be used to "jump" balls to different elevations in the ball run, which might be part of a strategy to lengthen the duration of the ball's path. To further explore the relationship between gravity, acceleration, and an inclined plane, see the Distance and Constant Acceleration project.

The Paper Ball Run was the 2022 Fluor Challenge. The official challenge has ended, but students can do this challenge for an independent science project at any time. NGSS-aligned lesson plans for the Paper Ball Run are available for grades 3-5, 6-8, and 9-12.

3. ### 3. Build a Wall Marble Run

Similar to the Paper Ball Run (described above), inclined planes may play a role in the design of a Wall Marble Run. With cardboard tubes, toilet paper rolls, and other craft and recycled materials, students can create a marble run attached to a wall or other vertical surface. Once the marble is placed into the run (at the beginning or at any other opening), it begins its descent. Strategic use of inclined planes can help control and lengthen the path of the marble. Questions: Can inclined planes be used to move a rolling marble to a higher elevation in the marble run? How do forces of motion and types of energy come into play in a marble run?

Build A Wall Marble Run!

### Lever

A lever involves a bar or beam that rests on a fulcrum that acts as a pivot point. When force is applied, the bar pivots on the fulcrum, and a force is created that lifts the load. The lever can amplify the applied force, making it possible to use smaller amounts of force (at a time) to lift the load. Both a car jack and a see-saw on a playground are familiar examples of a first class lever, a lever in which the fulcrum sits between the force and the load. There are three types of levers: first class, second class, and third class. These differ based on the position of the load, the fulcrum, and the force. The fulcrum is not always between the load and the force.

1. ### 4. Lifting a Load with a Single Finger

In the Lifting with a Lever lesson, students are given a ruler and a pencil and challenged to devise a way to lift a box of crayons with one finger. The simple machine solution is to use the ruler and pencil to make a lever. As students experiment with their levers, they will see how the positioning of the fulcrum between the applied force and the box of crayons (the load) changes the effort it takes to lift the crayons. Replacing the crayons with other (heavier or lighter) loads allows students to fully explore first class levers and the relationship between the fulcrum, the load, and the applied force. Questions: In this simple lever made from a ruler and a pencil, what two variables can be changed? Is it easier or harder to lift the crayons if the pencil (fulcrum) is positioned closer to the crayons? Why? Could you use one box of crayons to lift two boxes of crayons with the lever? How? (For a similar experiment with levers, try the Give It a Lift with a Lever activity. The activity uses coins to help visualize how the force required to lift a load changes in relation to the weight of the load or the distance of the force from the fulcrum.)

For additional STEM activities that involve levers, build and experiment with one of these fun DIY machines:

• Build a Popsicle Stick Catapult: What would change if the sticks were longer or if the fulcrum was positioned differently between the force and the load (closer to one end or the other)?
• Build a Cardboard Scissor Lift: Scissors use a first class lever. A scissor lift uses a series of levers to allow you to reach something far away. Applying force to one end moves the farthest end. Can you identify how the levers work?
• Duplicate Your Drawings with a Machine: A pantograph is a device that makes it possible to duplicate a drawing at a larger or smaller size. How many levers are involved in the construction of the device?

### Pulley

A pulley is a simple machine made from a rope looped around a wheel. When the rope is pulled from one side, the wheel turns with the rope, making it easier to lift the load. The advantage of a pulley is that it changes the direction of the force needed to lift or move the load. Lifting a load with a pulley involves pulling down on the rope, so you can use your own weight to help pull it down, rather than lifting the load up directly. A single pulley can be a powerful tool, but when more ropes and wheels are added (forming a compound pulley or pulley system), it takes even less effort to lift a load, but it takes more rope. (Keep in mind that the work remains the same.) A crane is a common construction machine that uses a pulley to lift heavy building materials.

1. ### 5. Pulling Pulleys to Lift a Load

In the Lighten the Load with a Pulley activity, students use an empty cardboard box (like a cereal box), pencils, paperclips, and string to experiment with pulleys. By setting up and testing individual and compound pulley systems, students observe the mechanical advantage offered using pulleys to lift a load and can see how the force required to lift a load decreases with a compound pulley, although the distance you have to pull the string increases. Questions: What other simple machine does a pulley use? How does the conservation of energy explain why using a pulley (or another simple machine) doesn't take less energy (or work) even if it makes the task seem easier? What role does friction play in the force required to use a pulley?

2. ### 6. Pulley'ing Your Own Weight

In the Pulley'ing Your Own Weight lesson, students use simple pulleys made from empty thread spools and string to explore how a pulley makes it easier to lift or move an object. The lesson guides an activity in which students investigate fixed and movable pulleys as well as pulley systems (made from more than one pulley). By experimenting with all three kinds, they make firsthand observations about how they differ and how they each function to help lift or move a load. Questions: What happens to the force required to lift something when multiple pulleys are used together? Not all pulleys are used to lift something. How does a bicycle chain use a pulley?

3. ### 7. Build a Ski Lift Pulley

In the Hit the Slopes: Build Your Own Ski Lift project, students build a model ski lift from simple materials. The challenge is to control the operation of the lift from only one side of the model so that the load is transported across a distance and dropped off on the other side. The solution for moving the load uses a system of pulleys. Students use the engineering design process to design and test their solutions as they explore both the operation of the pulleys and the other design requirements of the model being built. The pulley system in this experiment transports a load horizontally rather than lifting a load. Questions: What is the role of the paperclips in the model? Why does this model use two pulleys? What other everyday objects use a pulley system that moves in a continuous loop?

Build a Ski Lift from Office Supplies
Get inspired! This sixth-grade teacher built model ski lifts with her students to explore simple machines.

### Screw

A screw is an inclined plane that is wrapped around a center shaft (like a pole). A screw converts a turning motion into a forward force and can be used to hold things together or lift objects. A screw has threading around the shaft that helps it grip surrounding materials when it is “screwed” into place. These threads make it so that you have to unwind the screw (reverse the direction), to remove it. Screws used in construction hold materials together.

1. ### 8. Archimedes Screw

The Archimedes screw was originally developed by Archimedes to get rid of water on a boat. An Archimedes screw can also be used to move water from low-lying areas to higher elevations. In the Build an Archimedes Screw activity, students use tubing, a short length of pipe, and plastic containers to build an Archimedes screw and observe how each time the screw is rotated, more water enters the device, and the water is moved forward toward the collection point. Questions: How does the mechanical advantage of an inclined plane help explain how the Archimedes screw works? Why is the angle of the screw a critical factor in successfully using an Archimedes screw? What will happen if the angle is too steep? Students looking for an independent science project can explore with the Moving Water with the Archimedes Screw Pump project.

How to Make an Archimedes Screw - STEM Activity
Get inspired! This third-grade student turned the Archimedes screw into an Avatar-worthy waterbending project for the science fair!

### Wedge

A wedge is a simple machine that forces materials apart. A wedge amplifies force by having a larger area where the force is applied and a smaller area that concentrates the force. A nail, for example, has a larger head to which force is applied (striking it with a hammer) and a small point at the other end that will separate and enter the wood as a result of the applied force. Many everyday objects that have a blade or an edge used to separate things are examples of a wedge. This includes saws and even silverware. A wedge can also be used to hold objects together or to keep objects from moving, as demonstrated by a doorstop. Students will observe that a wedge is made of two inclined planes, but the purpose of the simple machine is different.

1. ### 9. Drilling Holes in Potatoes

In the A Simple Machine to Make Potato Holes activity, students investigate to find the easiest way to poke holes in raw potatoes using straws or pencils. The experiment guides students in testing an assortment of approaches and comparing the results to see which makes it easiest to drill holes and why. The solutions that work best involve wedges, which help concentrate the applied force to separate the potato and push the tool (straw or pencil) into the potato.

### Wheel and Axle

The wheel and axle work together to form a simple machine that helps reduce friction as objects move forwards or backwards across a surface. The wheel reduces friction as it rolls, and the axle (a rod the wheel rotates on) helps keep the wheel in line. Wheels and axles are common in cars, skateboards, office chairs, shopping carts, and other everyday objects that roll.

1. ### 10. Rubber Band Cars

In the Build a Rubber Band-Powered Car activity, students build a simple car from craft and recycled materials. The car gets its power from the energy stored and released from a wound rubber band. The design of the car is up to the students, and they can explore various materials for wheels and axles as well as creative designs for their cars. By experimenting with the wheels (both the material and the number of wheels), they can investigate how the size of the wheels may change how easily the car rolls over a surface.

Do More! For additional car science experiments and lessons, see Rev Up STEM Learning with Car Science Projects.
2. ### 11. Model a Car's Differential

In the Build a Differential from K'Nex® activity, students use the K'Nex toy building system to make a model differential. A differential is used in a car to allow wheels to spin independently. This allows them to spin at different speeds or even in different directions. The differential allows a car to turn. This activity doesn't directly deal with wheels as simple machines, but the wheel and axle are the foundation for examining how the differential helps control and enable movement in a modern car.

Build a K'Nex® Differential

## Engineering Challenges That Use Simple Machines

• ### 12. Rube Goldberg Machines

A Rube Goldberg machine is a device that performs a set of interconnected steps to complete a simple task. A ball might run down a ramp, trigger a sequence of dominoes, which then trigger another action, and so on. The sequence continues until the final task is completed. The Study Kinetic Energy with a Rube Goldberg Machine lesson guides educators in having students design and build Rube Goldberg machines in the classroom. The lesson focuses on NGSS-alignment related to kinetic energy, but the stages students incorporate into their Rube Goldberg devices might use a wide array of simple machines to put things in motion and trigger certain actions as the machine progresses to complete its final task.

The video below shows a simple Rube Goldberg machine in motion:

How To Build a Rube Goldberg Machine

After introducing them to types of simple machines, students can identify the simple machines in examples of Rube Goldberg machines they find online (and in the video example above). Then they can look for ways to use simple machines in their own Rube Goldberg machines. How many different simple machines can they add?

• ### 13. Design a Machine to Count the Seconds

After learning about individual types of simple machines and exploring how they offer a mechanical advantage when performing tasks, you can challenge students to put what they've learned to use by designing their own machine that makes use of simple machines. The Count the Seconds lesson outlines an engineering design challenge in which students design a device that can track a specific amount of time. Once the time has passed, the device should give a sound or visual signal. Students explore energy and energy transfer in their machines and use the engineering design process to design, test, and iterate.

• ### 14. Build a Water Lifting Machine

For another flexible STEM lesson in which students design and build a machine that may involve multiple simple machines, see the Build a Machine to Lift Water lesson. Students design and build their own water lifting machine. Individual designs may make use of one or more simple machines.

Build a Machine to Lift Water - STEM Lesson Plan

## Simple Machine Projects for Students Doing Independent Science Projects or Science Fair

Students interested in projects involving simple machines may enjoy independent physics and engineering projects like these:

## Related STEM Careers

As students get hands-on with simple machines, they can learn more about related STEM career paths with career profiles like:

For related educator resources, see:

## Vocabulary

The following word bank contains words that may be covered when teaching about simple machines using the lessons and activities in this resource.

• Axle
• Compound pulley
• Differential
• Engineering design
• Fixed pulley
• Force
• Forces of motion
• Friction
• Fulcrum
• Gears
• Inclined plane
• Kinetic energy
• Lever
• Movable pulley
• Newton's laws of motion
• Pivot
• Potential energy
• Pulley
• Rube Goldberg machine
• Screw
• Slope
• Simple machine
• Unbalanced forces
• Wedge
• Wheel
• Work

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## Understanding Science Buddies' STEM Resources

Lesson Plans contain materials to support educators leading hands-on STEM learning with students. Lesson Plans offer NGSS alignment, contain background materials to boost teacher confidence, even in areas that may be new to them, and include supplemental resources like worksheets, videos, discussion questions, and assessment materials.

Video Lessons include NGSS alignment and offer a plug-and-play option for teaching a STEM lesson. Each Video Lesson asks a science question, teaches students about the relevant science, and guides students in a hands-on experiment that will help them answer the question. Video Lessons are NGSS-aligned and bring core science concepts to life with storytelling, animation, and photos using a self-paced engage, explore, and reflect format.

Activities are simplified explorations that can be used in the classroom or in informal learning environments.

Projects are written to support students doing independent science projects or science fair projects. Projects can be adapted for classroom use.

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