Science · Grade 6 · Flight: Principles and Innovation · Term 2

Bernoulli's Principle and Lift

Students explore Bernoulli's principle and its application in generating lift for flight.

• Ontario Curriculum Expectations
• MS-PS2-2

About This Topic

Bernoulli's principle states that as the speed of a fluid, such as air, increases, its pressure decreases. Airplane wings have a curved upper surface and flatter lower surface, so air moves faster over the top. This creates lower pressure above the wing and higher pressure below, producing an upward lift force essential for flight. Students investigate this principle through observations and experiments, aligning with curriculum goals to explain how wing shape generates lift.

In the flight unit, this topic links forces and motion to aeronautical design. Students design simple experiments to test air speed and pressure relationships, developing skills in prediction, data collection, and analysis. Understanding lift prepares them for exploring innovation in aviation and applies scientific principles to everyday observations like soaring birds or paper gliders.

Active learning benefits this topic greatly because invisible air pressures become visible through student-led demos. When students blow air over paper strips or test wing models, they witness lift firsthand, connect cause to effect, and refine their explanations through peer discussion and iteration.

Key Questions

1. Explain how the shape of a wing generates lift according to Bernoulli's principle.
2. Design a simple experiment to demonstrate Bernoulli's principle.
3. Analyze the relationship between air speed and pressure in creating lift.

Learning Objectives

• Explain how the shape of an airfoil creates a difference in air pressure, resulting in lift.
• Analyze the relationship between air speed and air pressure using experimental data.
• Design and build a simple model that demonstrates Bernoulli's principle.
• Compare the lift generated by different wing shapes through experimentation.

Before You Start

Forces and Motion

Why: Students need a foundational understanding of forces, including push and pull, and how they affect an object's motion.

Properties of Air

Why: Understanding that air is a fluid with mass and exerts pressure is essential for grasping Bernoulli's principle.

Key Vocabulary

Bernoulli's Principle	A principle stating that for an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy.
Lift	The component of a force, particularly an aerodynamic force, that is perpendicular to the direction of motion.
Airfoil	The cross-sectional shape of a wing, blade, or sail, designed to produce lift when moving through a fluid.
Air Pressure	The force exerted by air molecules on a surface, which decreases as the speed of the air moving over that surface increases.

Watch Out for These Misconceptions

Common Misconception

Lift comes only from wings flapping like a bird's.

What to Teach Instead

Fixed wings on airplanes generate lift through pressure differences, not flapping. Hands-on demos with stationary paper wings under airflow help students see lift without motion, prompting them to revise ideas through group predictions and observations.

Common Misconception

Air pressure is the same above and below the wing.

What to Teach Instead

Wing shape causes air to speed up over the top, lowering pressure there. Experiments like the straw-and-paper demo let students feel and visualize this difference, with peer discussions clarifying why the paper rises.

Common Misconception

Lift requires the plane to move forward; stationary wings cannot lift.

What to Teach Instead

Relative airflow creates lift, as shown by fans blowing over stationary models. Student testing of wing models reveals this, building confidence in the principle through repeated trials and shared evidence.

Active Learning Ideas

Demonstration: Straw and Paper Strip

Give each pair a straw and strip of paper. Students hold the paper near the straw's top and blow air across the top edge. Observe the paper lift upward. Pairs record predictions and explanations, then share with the class.

20 min·Pairs

Experiment: Fan and Wing Models

Students construct paper wings with varying camber using templates. Place wings on a balance under a fan and measure lift by noting deflection. Groups change wing shapes and compare results in data tables.

45 min·Small Groups

Design Challenge: Optimized Gliders

Teams design and build paper gliders emphasizing wing shape for lift. Test flights across the room, measure distances, and adjust designs based on Bernoulli predictions. Class compiles average data for analysis.

50 min·Small Groups

Stations Rotation: Pressure Demos

Set up stations with ping-pong ball in hairdryer stream, suspended balloon between blowers, paper tunnel collapse, and wing lift model. Groups rotate, observe, and note pressure effects at each.

40 min·Small Groups

Real-World Connections

• Pilots and aerospace engineers use Bernoulli's principle daily to design aircraft wings that generate sufficient lift for safe takeoff, flight, and landing.
• The design of wind turbine blades incorporates airfoil shapes to capture wind energy efficiently, converting air movement into electrical power.
• Sailboat designers manipulate sail shapes to create lift from the wind, allowing boats to move forward even when the wind is not directly behind them.

Assessment Ideas

Exit Ticket

Provide students with a diagram of an airplane wing cross-section. Ask them to label the areas of higher and lower pressure and write one sentence explaining why this pressure difference creates lift.

Quick Check

Ask students to hold a strip of paper horizontally just below their lower lip. Instruct them to blow firmly across the top of the paper. Ask: 'What happened to the paper, and why did it happen?'

Discussion Prompt

Pose the question: 'Imagine you are designing a kite. How would you shape the kite to make it fly higher, and what scientific principle are you using?' Facilitate a brief class discussion on their ideas.

Frequently Asked Questions

How does Bernoulli's principle explain lift on airplane wings?

Bernoulli's principle notes that faster-moving air over the curved top of a wing creates lower pressure than slower air below. This pressure imbalance pushes the wing upward. Students grasp this best by linking it to experiments where they see paper or balls rise in fast airflow streams.

What simple experiment demonstrates Bernoulli's principle?

A classic demo uses a straw and paper strip: blow smoothly over the top of the hanging strip, and it lifts toward the stream due to lower pressure. Variations include hairdryers lifting ping-pong balls. These quick setups reveal the principle without complex equipment.

How can active learning help students understand Bernoulli's principle and lift?

Active learning engages students through hands-on demos like building wing models or testing gliders, making abstract pressure concepts observable. They predict outcomes, test variables such as wing shape, collect data, and discuss results in groups. This process strengthens connections to flight, improves retention, and builds inquiry skills over passive lectures.

What role does wing shape play in generating lift?

The airfoil shape forces air to travel farther and faster over the top surface, reducing pressure there per Bernoulli's principle. Students explore this by modifying paper wings and measuring lift under fans, seeing how camber affects performance and applying it to glider designs.