Physics and Chemistry · 6th Year · Energy and Forces: Light and Sound · 2.º Período

The Nature of Light

Students investigate how light travels, reflects, and refracts. They explore the visible spectrum and how we perceive colour.

TL;DR:In this unit, students explore the fundamental properties of light, including its travel in straight lines and its behavior when encountering different surfaces. The NCCA curriculum emphasizes 'Investigating and experimenting,' which here involves using mirrors for reflection and lenses or water for refraction. Students also delve into the visible spectrum, discovering how white light is composed of many colors.

• NCCA Curriculum Specifications
• SESE Science: Energy and forces - Light
• SESE Science: Working Scientifically - Investigating and experimenting

About This Topic

In this unit, students explore the fundamental properties of light, including its travel in straight lines and its behavior when encountering different surfaces. The NCCA curriculum emphasizes 'Investigating and experimenting,' which here involves using mirrors for reflection and lenses or water for refraction. Students also delve into the visible spectrum, discovering how white light is composed of many colors.

This topic links to the history of science and technology, from the invention of the telescope to modern fiber optics. It encourages students to question their own perceptions of the world. This topic is best taught through station rotations where students can manipulate light sources and observe effects firsthand rather than looking at diagrams.

Key Questions

1. How does light travel through different mediums?
2. What happens when light hits a mirror or a prism?
3. Why do objects appear to have different colours?

Watch Out for These Misconceptions

Common Misconception

We see because light comes out of our eyes.

What to Teach Instead

This is a common ancient belief. Using a 'black box' experiment where students try to see an object with no light source helps them realize light must enter the eye from an external source.

Common Misconception

Light only reflects off mirrors.

What to Teach Instead

Light reflects off everything we can see. Peer discussion about why we can see a wooden table versus a mirror helps students understand the difference between diffuse and specular reflection.

Active Learning Ideas

Stations Rotation

Light Lab

Stations include: 1) Using mirrors to hit a target with a beam, 2) Observing a pencil 'break' in a glass of water, and 3) Creating a rainbow with a prism. Students record their 'laws of light' at each stop.

50 min·Small Groups

Inquiry Circle

Periscope Design

Students work in pairs to design and build a working periscope using cardboard tubes and small mirrors. They must calculate the angles needed to see over a barrier.

45 min·Pairs

Think-Pair-Share

The Color of Shadows

The teacher shows a shadow cast by a colored light. Students discuss in pairs why the shadow is a certain color and how light blocking works before sharing with the class.

15 min·Pairs

Frequently Asked Questions

What are the best hands-on strategies for teaching light?

Station rotations are excellent for light. By providing different tools at each station, mirrors, prisms, lenses, and water tanks, students can discover the rules of reflection and refraction through trial and error. This inquiry-based approach makes the 'straight line' travel of light much more obvious than a lecture would.

How does a prism make a rainbow?

A prism slows down different colors of light by different amounts, causing them to bend (refract) at different angles. This separates the white light into its component colors.

What is the difference between transparent, translucent, and opaque?

Transparent materials let all light through, translucent materials let some light through but scatter it, and opaque materials block all light.

Why does a straw look bent in water?

This is due to refraction. Light travels at different speeds in air and water, which causes the light rays to bend as they change medium, tricking our eyes.