Kids use simple machines every day, from the toy cars they play with, to the plastic shovels they use in the sandbox, to the slides they zoom down at the playground. But just using a simple machine isn’t quite the same as understanding it in an engineering context. Learning how simple machines function and improve our everyday lives is an asset that can help students better understand the world around them. Here’s what you need to know about the six simple machines and how to introduce them in STEM activities.
The Six Simple Machines
Seen as the backbone of mechanical engineering, simple machines are basic mechanical devices consisting of one or two components that make physical tasks, such as lifting and moving objects, much easier. As we’ll see, simple machines can be used on their own or can be combined into more complex machines to amplify input force and increase mechanical advantage. In other words, simple machines produce more force than is put into them. The six fundamental simple machines are:
Inclined Plane
As the name suggests, an inclined plane is simply an angled surface used to move large or heavy loads, like a ramp used to move furniture from a moving truck. The inclined plane is most useful for objects that are difficult to lift, enabling them to be moved with minimal effort. The angle of an inclined plane does influence the amount of effort needed to move a load: lower angles will require less effort than a steep incline.
Wheel and Axle
The wheel and axle is a two-part simple machine that consists of a circular disc (the wheel) and a cylindrical rod that passes through its center (the axle). The wheel can either be fixed to the axle for simultaneous motion (like a bike wheel) or rotate around it (like a pizza cutter). Wheels and axles are found everywhere—from doorknobs to car tires—and facilitate movement by reducing friction.
Lever
Levers have been used for thousands of years to help lift heavy loads. A lever consists of a beam that is balanced on a support, called the fulcrum. For example, a seesaw is a lever with the fulcrum positioned in the middle. Any downward force on one end of a seesaw will cause an upward motion on the other side. Crowbars and bottle openers are examples of levers where the fulcrum is positioned closer to the load, which requires minimal effort to move or lift weight.
Pulley
A pulley is a simple machine used to move objects vertically or horizontally. Typically, a pulley consists of a grooved wheel with a rope or cable placed around it. In its simplest form, a pulley functions by securing a load to one end of the rope and pulling on the other end of the rope to lift the load up (like a bucket of water in a well). It is also possible to combine multiple pulleys to lift very heavy loads with little effort. For example, construction cranes and elevators use pulley systems to lift and lower large loads with ease.
Wedge
The wedge is made up of two inclined planes, which create a triangular shape with a tapered point. When force is applied to the wider plane of the wedge, it forces the tapered edge into or under something with little effort. For example, when an axe strikes a log of wood, the pointed edge penetrates the wood, while the wider base of the axe helps to split and separate the wood. Wedges can also be used to keep an object from moving, like a door stop.
Screw
The screw is made up of an inclined plane that is wrapped around a cylindrical core. It is designed to convert rotational motion (turning) into linear motion (moving up and down) and can be used to multiple ends. For instance, screws are used to securely attach objects together (like a jar and lid, or a screw securing two pieces of wood together), and they are also helpful for lifting heavy objects (like a jackscrew) and drilling holes.
Simple Machine Activities and Experiments for Students
Understanding simple machines is foundational to learning about complex engineering concepts and, more generally, how things in the world function. It’s therefore important to introduce simple machines to students from a young age using interactive and practical activities. Sphero’s Blueprint lessons are a great place to start, as they help students make and use simple machines and then build on that knowledge by combining them and applying them to real-world scenarios. Below, we’ll walk through a few examples of lessons that can be taught using the Blueprint Build Kit.
In a level 1 foundational Blueprint lesson, students are invited to build an inclined plane and experiment with different angles to see what makes it easier or harder to move a load. The level 2 lesson builds on this knowledge, asking students to first theorize how the ancient Egyptians used inclined planes to build the pyramids and then build a small-scale model using the simple machine.
To understand pulleys, students can start by building a simple well structure using Blueprint building blocks and rope to see the mechanical advantage that using a pulley can have. The following lesson adds complexity by combining multiple pulleys and different types of motion in a construction crane prototype. In teams, students can assemble the crane to understand the functions of pulleys in a real-world application.
In the screw lesson, students are first tasked with building a simple vise controlled by a lead screw using a Blueprint kit. From there, they will be equipped to build a more complicated motorcycle lift that integrates screws and levers. This machine can be tested in class using a book or other objects to demonstrate how it functions and what mechanical advantage it offers. More Blueprint lessons for simple machines can be found here.
Real-World Applications of Simple Machines
Ultimately, learning about simple machines in the classroom will equip students with vital knowledge and practical skills that can be applied in a wide variety of ways as they continue their education and move into various professions. Introducing simple machines not only as concepts but as hands-on devices will help reinforce a deeper understanding of them and enable students to really master the building blocks of all mechanical engineering systems and machines.
About the Author
The Sphero Team
The Sphero Team is comprised of current and former educators, education content and curriculum writers, product designers, engineers, executive leadership, and other experts in their fields. Learn more about who we are and what we do at sphero.com/about.
