Physics · 9th Grade

Active learning ideas

Speed and Velocity

Active learning works for this topic because students need to SEE the difference between speed and velocity through motion, not just hear about it. Dropping objects and watching graphs form helps them feel the constant pull of gravity and the impact of air resistance in real time.

• Common Core State Standards
• HS-PS2-1
• CCSS.MATH.CONTENT.HSF.IF.B.6

• 20–40 min
• Pairs → Whole Class
• 3 activities

Activity 01

• Inquiry Circle
• 30 min · Small Groups

Inquiry Circle: The Great Drop

Students drop pairs of objects with different masses but similar shapes (like a heavy ball and a light ball) from a height. They use slow-motion video on their phones to determine if they hit the ground at the same time.

Differentiate between average speed and average velocity using a round trip example.

Facilitation Tip

During The Great Drop, have students predict which ball will hit the ground first and time each drop three times to build consensus before revealing the vacuum chamber results.

What to look for

Present students with a scenario: A student walks 5 meters east, then 5 meters west, taking 10 seconds total. Ask: 'What is the student's average speed? What is the student's average velocity? Explain your answers.'

• Analyze
• Evaluate
• Create
• Self-Management
• Self-Awareness

Activity 02

• Simulation Game
• 40 min · Small Groups

Simulation Game: Terminal Velocity Design

Using coffee filters, students experiment with how surface area and mass affect the time it takes to reach the floor. They must design a 'parachute' that results in the slowest possible descent, modeling terminal velocity.

Explain how an object can have a high speed but zero average velocity.

Facilitation Tip

In Terminal Velocity Design, ask students to adjust only one variable at a time to isolate how shape, mass, or surface area affects descent time.

What to look for

Provide students with a simple position-time graph showing an object moving back and forth. Ask them to: 1. Identify the time interval when the object's speed was highest. 2. Calculate the object's average velocity over the entire trip.

• Apply
• Analyze
• Evaluate
• Create
• Social Awareness
• Decision-Making

Activity 03

• Think-Pair-Share
• 20 min · Pairs

Think-Pair-Share: Gravity on Other Worlds

Students are given the gravitational acceleration for the Moon and Mars. They must calculate how much longer it would take a rock to fall 10 meters on those worlds compared to Earth and discuss the implications for astronauts.

Predict the instantaneous velocity of an object from a position-time graph.

Facilitation Tip

For Gravity on Other Worlds, assign each pair a different planet’s gravity value and ask them to predict how their object’s motion would change there.

What to look for

Pose the question: 'Can an object have a high speed but a zero average velocity? Describe a real-world situation where this occurs and explain why.'

• Understand
• Apply
• Analyze
• Self-Awareness
• Relationship Skills

A few notes on teaching this unit

Teach this topic by starting with what students can feel: dropping two objects side-by-side. Use graphs to show how velocity changes while speed can stay constant. Avoid teaching formulas too early; let students derive g = 9.8 m/s² from their own data first. Research shows that linking math to physical experience reduces misconceptions about acceleration.

Successful learning looks like students predicting, observing, and explaining why two different masses reach the ground at the same time in a vacuum. They should also distinguish speed from velocity by describing direction and calculating changes over time with units and signs included.

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Watch Out for These Misconceptions

• During Collaborative Investigation: The Great Drop, watch for students who assume the heavier ball will hit the floor first even after seeing the vacuum chamber demonstration.

  Ask the group to re-examine their data tables and compare the fall times for both masses in the regular drop versus the vacuum chamber. Have them explain why the times match in one case but not the other.

• During Think-Pair-Share: Gravity on Other Worlds, watch for students who believe gravity stops acting at the peak of an object’s flight.

  During the pair discussion, remind students to sketch a velocity vs. time graph for an object thrown upward and label where velocity is zero but acceleration is still -9.8 m/s². Use this to correct their thinking before sharing with the class.

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Methods used in this brief

• Inquiry Circle
• Simulation Game
• Think-Pair-Share