GUEST BLOGGER CHRISTINE VAN ZANDT
To help make tasks easier, people use simple machines such as levers. My book, The Legendary Life Story of the Lever: How a Deceptively Simple Machine Moves the World Forward, features levers used throughout history. For example:
- Ice Age: Levers propelled spear thrower farther and faster.
- Ancient Egypt: As a beam on a balance scale, levers helped weigh items at marketplaces.
- Ancient China: As a pole, levers helped move rocks to build the Great Wall of China.
- Ancient Greece: As the throwing arm of a catapult, levers were used in battles. An easy-to-build model of a catapult is included in my book.
- The Renaissance: In the printing press, cranking lever turned a screw that then inked the paper.
- The Tudor Period: A drawbridge, also known as a “bascule bridge” (the French word meaning “seesaw”). Heavy spans are moved by placing counterweights on one side of the pivot point (fulcrum).
- The Industrial Revolution: Trains used levers as connecting rods to make the wheels turn.
- World War II: A fighter plane’s throttle was a lever..
- Golden Age of Hollywood: The hinged clapper stick on a clapperboard is a lever.
- Space Age: The Space Shuttle Atlantis used a lever as a robotic arm.
There are three kinds of levers. For our Project-Based Learning (PBL) exercise, we will use a first-class lever.
Driving question
How can you use a lever to move a heavy object?
Let the students review this image to the right. Explain that the lever functions as a pole to help move heavy objects. To do this, an object such as a small rock is positioned under the pole. The rock is the pivot point or fulcrum. The pole is wedged under the heavy object (the load). When a person applies pressure to the end of the pole, this force lifts the load.
Project objective
Use a ruler and a rectangular eraser to move or tilt up (onto its end) a heavy textbook.
Activity
Ask students to figure out how to position the eraser as the pivot point or fulcrum, then use the ruler to move the heavy object. Ask them to record their observations after each trial.
Extension
Individual or group project using a ruler as a lever. Change the eraser for a larger pivot point such as a ball of Playdough (which can change shape and size). Ask students to vary where they place the fulcrum on the ruler. Talk about or write down which combination works best.
Vocabulary
Have the students heard the word “leverage”?
- Definition as a noun (from Merriam-Webster): the action of a lever or the mechanical advantage gained by it. Example: Use a pole for leverage to move a rock.
- Definition as a verb: to use (something such as skills or influence) to achieve or enhance a desired result. Example: The star leveraged her popularity to sell her line of clothing.
Simple machines
A lever is a simple machine. There are six kinds of simple machines:
- Lever
- Inclined plane
- Wedge
- Wheel and axle
- Screw
- Pulley
Other first-class levers
- A balance scale. The load is placed in one pan and the effort is placed in the other pan. The fulcrum, or the central pivot point, supports the beam. A weight placed on one pan (the effort) lifts what is in the other pan (the load). When both sides are equal, the beam’s arms are level.
- Seesaws (teeter-totters). The fulcrum is the part beneath the middle of the seesaw, a pivot point where the beam rests and rotates. When someone sits on one end of the seesaw, this pushing down applied force is called the effort. The person on the other side of the seesaw (the load) is lifted due to the rotational motion around the fulcrum.
Bonus question
Ask students, are scissors levers?
Yes! The two blades of the scissors pivot around the screw (fulcrum) that holds the scissors together. When you place your fingers in a pair of scissors and squeeze, you are applying the effort that will cut the load.
Featured image credit: “My scissor collection” by Bekathwia. Licensed under CC BY-SA 2.0.
Christine Van Zandt is a freelance editor, writer, and award-winning author of five nonfiction picture books. You can also find her stories and poems in anthologies and magazines. She lives in Los Angeles with her family. Find her online at christinevanzandt.com, X/Twitter, LinkedIn, Facebook, Instagram, and Bluesky.
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