Principles of Physics: Exploring the Physical World · 6th Year

Active learning ideas

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.

• NCCA Curriculum Specifications
• NCCA: Primary - Energy and Forces

• 20–45 min
• Pairs → Whole Class
• 4 activities

Activity 01

• 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.

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.

What to look for

Provide students with a scenario: 'Imagine dropping a flat sheet of paper and a crumpled ball of paper from the same height. Which will hit the ground first, and why?' Students should write a brief explanation referencing gravity and air resistance.

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

Activity 02

• 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.

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.

What to look for

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 significant role. Follow up with a brief class discussion on their reasoning.

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

Activity 03

• 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.

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.

What to look for

Pose the question: 'If we could remove all the air from a room, what would happen to the fall time of a feather compared to a stone dropped from the same height?' Facilitate a discussion where students explain their predictions based on their understanding of gravity and air resistance.

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

Activity 04

• 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.

Why do all objects fall towards the ground?

What to look for

Provide students with a scenario: 'Imagine dropping a flat sheet of paper and a crumpled ball of paper from the same height. Which will hit the ground first, and why?' Students should write a brief explanation referencing gravity and air resistance.

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

A few notes on teaching this unit

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.

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.

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Watch Out for These Misconceptions

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

  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.

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

  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.

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

  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.

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Methods used in this brief

• Inquiry Circle