Gravity's Pull and Falling Objects

Active learning lets students feel gravity’s pull firsthand, turning abstract concepts into observable evidence. Hands-on drops and challenges make the counterintuitive idea—equal acceleration for all objects in a vacuum—memorable and debatable among peers.

• 6th Year
• Principles of Physics: Exploring the Physical World
• 4 activities
• 20 min–45 min

Learning Objectives

1. Compare the acceleration of different objects when dropped, accounting for air resistance.
2. Explain the role of gravity as a universal force acting on all objects with mass.
3. Analyze experimental data to identify the relationship between an object's shape and its terminal velocity.
4. Predict how changes in air density might affect the fall rate of objects.
5. Design a simple experiment to demonstrate the effect of air resistance on falling objects.

Inquiry Circle

⏱ 30 min·Pairs

Drop Test Relay: Object Races

Pairs select objects like coins, feathers, balls, and crumpled paper. Drop one pair at a time from a fixed height, such as two meters, using stopwatches to time falls. Switch roles and record three trials per object, then compare averages on a class chart.

Prepare & details

Why do all objects fall towards the ground?

Facilitation Tip: During the Drop Test Relay, have students call out starting and stopping times aloud to reinforce timing precision.

Setup: Groups at tables with access to source materials

Materials: Source material collection, Inquiry cycle worksheet, Question generation protocol, Findings presentation template

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

Inquiry Circle

⏱ 45 min·Small Groups

Parachute Challenge: Shape Effects

Small groups build parachutes from plastic bags, string, and toys, varying size and shape. Drop from a height, timing descent. Adjust designs based on first trials, test again, and discuss why flat versus cupped shapes fall differently.

Prepare & details

How does the shape of an object affect how fast it falls?

Facilitation Tip: For the Parachute Challenge, remind groups to measure the same drop height for every trial to control variables.

Setup: Groups at tables with access to source materials

Materials: Source material collection, Inquiry cycle worksheet, Question generation protocol, Findings presentation template

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

Inquiry Circle

⏱ 20 min·Whole Class

Whole Class Demo: Vacuum vs Air

Show a video of Apollo 15 hammer-feather drop on the moon, then replicate in class with tall tube and vacuum pump if available, or coin and feather. Class predicts outcomes, times drops with and without air, and votes on explanations.

Prepare & details

What happens if you drop a feather and a stone at the same time (and why might they fall differently)?

Facilitation Tip: In the Whole Class Demo, lower the vacuum chamber slowly to let students observe the feather’s motion before and after air removal.

Setup: Groups at tables with access to source materials

Materials: Source material collection, Inquiry cycle worksheet, Question generation protocol, Findings presentation template

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

Inquiry Circle

⏱ 35 min·Individual

Graphing Falls: Data Stations

Individuals or pairs drop objects at stations with different heights. Plot time versus height on graphs. Share graphs in plenary to identify straight-line trends showing constant acceleration.

Prepare & details

Why do all objects fall towards the ground?

Setup: Groups at tables with access to source materials

Materials: Source material collection, Inquiry cycle worksheet, Question generation protocol, Findings presentation template

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

Teaching This Topic

Teach this topic by letting students generate their own questions about falling objects, then providing tools to test those questions. Avoid telling them the answers upfront; instead, guide them to collect data that contradicts their initial ideas. Research shows this approach builds stronger conceptual understanding than direct instruction alone. Move between small-group experiments and whole-class discussions to help students connect their observations to the underlying physics.

What to Expect

Students will explain that gravity causes all objects to accelerate at 9.8 m/s² toward Earth while identifying air resistance as the variable that alters fall speed. They should use evidence from their experiments to justify predictions about different objects’ fall times.

Watch Out for These Misconceptions

Common Misconception

During the Drop Test Relay, watch for students assuming the heaviest object will always win the race.

What to Teach Instead

After the relay, have groups compare timing data for objects of similar shape but different mass. Prompt them to notice that coins and marbles reach the ground at nearly the same time, using this evidence to revise their initial claims during a class discussion.

Common Misconception

During the Graphing Falls activity, listen for students attributing faster acceleration to heavier objects.

What to Teach Instead

During data analysis, ask pairs to calculate acceleration values from their graphs. When students see similar slopes for varied masses, guide them to recognize that gravitational force increases with mass, but acceleration does not, correcting the misconception with shared numerical evidence.

Common Misconception

During the Parachute Challenge, note if students believe air resistance can completely stop an object’s fall.

What to Teach Instead

After testing parachutes, ask groups to measure terminal velocity by timing how long it takes for each parachute to fall a fixed distance. Use these measurements to show that while air resistance slows the fall, gravity continues to act, leading to a constant speed rather than a halt.

Assessment Ideas

Exit Ticket

After the Drop Test Relay, provide a scenario: 'A crumpled paper ball and a flat sheet are dropped from the same height. Which hits the ground first, and why?' Students should reference gravity and air resistance in their written response.

Quick Check

During the Whole Class Demo, ask students to hold up one finger if they think gravity is the only force acting on a falling feather, and two fingers if they think air resistance also plays a role. Circulate to note misconceptions and address them in the debrief.

Discussion Prompt

After the Parachute Challenge, pose the question: 'If we removed all air from the room, would a feather and a stone fall at the same rate? Explain your prediction based on what you observed.' Facilitate a discussion where students use their parachute data to support their answers.

Extensions & Scaffolding

• Challenge: Ask students to design a third parachute that falls faster than their original two but slower than a no-parachute drop, then test and refine it with peers.
• Scaffolding: Provide pre-labeled graphs with axes for distance and time so students focus on plotting their data rather than setting up scales.
• Deeper: Have students research how skydivers use body position and parachute design to control terminal velocity, then present their findings to the class.

Key Vocabulary

Gravity	A fundamental force of attraction that exists between any two objects with mass. On Earth, it pulls all objects towards the planet's center.
Acceleration due to gravity	The constant rate at which objects accelerate towards Earth when falling, approximately 9.8 meters per second squared, in the absence of air resistance.
Air resistance	A type of friction, or drag, that opposes the motion of an object through the air. It depends on the object's shape, size, and speed.
Terminal velocity	The constant speed that a freely falling object eventually reaches when the resistance of the medium through which it is falling prevents further acceleration.