Physics · 9th Grade

Active learning ideas

Simple Machines: Levers and Pulleys

Active learning works because levers and pulleys demand hands-on exploration of force, distance, and energy trade-offs. When students manipulate real machines, they directly experience how mechanical advantage changes effort without altering total work. This tactile engagement turns abstract physics into memorable, testable understanding.

• Common Core State Standards
• HS-PS3-3
• HS-ETS1-2

• 30–50 min
• Small Groups
• 3 activities

Activity 01

• Stations Rotation
• 40 min · Small Groups

Lab Investigation: Lever Classes and Mechanical Advantage

Students set up levers with a ruler and fulcrum to balance loads at different positions. They measure the input and output forces using spring scales and calculate the mechanical advantage for each configuration, then classify which lever class each represents.

How can a machine multiply force without violating the law of conservation of energy?

Facilitation Tip

During the Lever Classes and Mechanical Advantage lab, circulate with a spring scale to ensure students read force values at consistent distances from the fulcrum.

What to look for

Provide students with diagrams of different lever and pulley configurations. Ask them to calculate the ideal mechanical advantage for each and identify the class of lever shown.

• Remember
• Understand
• Apply
• Analyze
• Self-Management
• Relationship Skills

Activity 02

• Stations Rotation
• 50 min · Small Groups

Design Challenge: Build a Pulley System to Lift a Load

Groups are given a target load and must design a pulley system that allows one person to lift it using less than half the actual weight. They sketch the pulley arrangement, predict the mechanical advantage, build and test it, then compare measured efficiency to theoretical values.

Why is there always a trade-off between force and distance in simple machines?

What to look for

Pose the question: 'If a simple machine gives you a mechanical advantage greater than 1, meaning it multiplies your force, how can this happen without violating the law of conservation of energy?' Guide students to discuss the trade-off between force and distance.

• Remember
• Understand
• Apply
• Analyze
• Self-Management
• Relationship Skills

Activity 03

• Gallery Walk
• 30 min · Small Groups

Gallery Walk: Levers in the World

Stations feature images of real-world lever applications: scissors, wheelbarrows, tweezers, seesaws, and construction cranes. Student groups identify the class of lever, locate the fulcrum, effort, and load, and calculate the mechanical advantage using dimensions given. Groups rotate and leave written comments on each other's analyses.

How did ancient civilizations use levers to build massive structures like the pyramids?

What to look for

Ask students to draw one simple machine (lever or pulley) they might use to make a task easier. They should label the fulcrum (if applicable), effort, and load, and briefly explain how it provides mechanical advantage.

• Understand
• Apply
• Analyze
• Create
• Relationship Skills
• Social Awareness

A few notes on teaching this unit

Teach levers and pulleys by grounding abstract principles in concrete measurement. Avoid lectures that separate force from distance; instead, let students discover the conservation of energy through data. Research shows students grasp mechanical advantage better when they calculate it themselves from real forces and distances rather than memorizing formulas.

Successful learning looks like students confidently identifying lever classes, calculating mechanical advantage, and explaining why pulleys reduce effort only in specific setups. They should articulate the trade-off between force and distance and apply these concepts to real-world engineering challenges. Misconceptions should be replaced with evidence from their own measurements.

---

Watch Out for These Misconceptions

• During the Lever Classes and Mechanical Advantage lab, watch for students who assume a higher mechanical advantage means more total work is done.

  During this lab, have students calculate input and output work using their measured forces and distances. Ask them to compare the two values and discuss how work is conserved despite changes in force and distance.

• During the Build a Pulley System to Lift a Load challenge, watch for students who believe a single fixed pulley reduces effort force.

  During this challenge, provide both fixed and movable pulleys. Have students measure the effort force required for each setup and compare it to the load weight to show that only movable pulleys reduce effort.

---

Methods used in this brief

• Stations Rotation
• Gallery Walk