Class: Senior Secondary School 1 (SS1 / SSS 1)
Term: 1st Term
Week: 7
Age: 15 years
Duration: 45 minutes
Subject: Photography
Curriculum Theme: Trade
Previous Lesson: The Theory Of Light: Sources And Importance To Photography.
Topic: PROPERTIES OF LIGHT
Subject Matter: Absorption, Reflection, Refraction, Dispersion

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:

Define absorption, reflection, refraction, and dispersion of light.
State the differences between specular and diffuse reflection.
Explain how light behaves when it passes through different media.

Affective Domain:

Appreciate the importance of understanding light properties in photography.
Develop an interest in observing light phenomena in their environment.

Psychomotor Domain:

Demonstrate the reflection of light using a mirror.
Conduct simple experiments to show light refraction and absorption.

Work collaboratively in groups to observe and discuss light properties.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Senior Secondary Schools.
State Unified Scheme of Work for Photography (SSS 1).
Any relevant Photography textbook for Senior Secondary Schools (e.g., MacMillan Senior Secondary Photography).

Instructional Materials

The teacher will teach this lesson with the aid of:

Mirror
Prism
Glass cup
Coloured paper
Torchlight or sunlight

Rationale for the Lesson

Understanding the properties of light helps pupils to know how light interacts with objects and surfaces. This knowledge is important for photographers to control and manipulate light effectively, leading to better photographs and a deeper appreciation of visual phenomena.

Prerequisite/Previous Knowledge

Pupils have a basic understanding of light as a form of energy and can identify various sources of light.

Lesson Content/Board Summary

PROPERTIES OF LIGHT

Absorption of Light

Absorption of light is the process where light energy is taken in by a material and converted into other forms of energy, usually heat. When light is absorbed, it does not pass through or reflect off the material.

The following are factors affecting absorption:

Colour of the object: Darker objects absorb more light, while lighter objects reflect more.
Type of material: Different materials have varying absorption rates.

Reflection of Light

Reflection of light is the bouncing back of light rays when they strike a surface. This is how we see objects that do not produce their own light.

The following are types of reflection:

Specular Reflection: Occurs when light reflects off a smooth, polished surface (like a mirror) in a single, clear direction, forming a sharp image.
Diffuse Reflection: Occurs when light reflects off a rough or uneven surface, scattering the light in many different directions. This allows us to see non-shiny objects from various angles.

Refraction of Light

Refraction of light is the bending of light rays as they pass from one transparent medium to another of different optical densities. This bending occurs because light changes speed when moving between different media (e.g., from air to water or glass).

The following are examples of refraction:

A spoon appearing bent when placed in a glass of water.
The apparent shallowing of a swimming pool.

Dispersion of Light

Dispersion of light is the phenomenon where white light splits into its constituent colours (spectrum) when it passes through a prism or water droplets. This happens because each colour of light (with a different wavelength) travels at a slightly different speed through the medium, causing them to bend at different angles.

The following are the colours of the visible spectrum:

Red
Orange
Yellow
Green
Blue
Indigo
Violet (ROYGBIV)

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher introduces the topic by asking pupils to observe how light behaves in the classroom, for example, light passing through a window, reflecting off a shiny surface, or being absorbed by dark curtains. The teacher then asks what happens to light when it hits different objects.
Pupils’ Activity: Pupils observe and share their ideas about how light interacts with different objects.
Learning Point: Pupils recall prior knowledge about light and are introduced to the concept of light properties.

Step 2: Presentation of Absorption of Light

Time: 7 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher explains the meaning of absorption of light, using coloured paper (e.g., black and white) to demonstrate how different colours absorb varying amounts of light. The teacher explains that absorbed light is converted to heat.
Pupils’ Activity: Pupils listen attentively and observe the demonstration, asking questions for clarification.
Learning Point: Pupils understand what absorption of light is and how it relates to object colour.

Step 3: Presentation of Reflection of Light

Time: 7 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher defines reflection of light and demonstrates it using a mirror and a torchlight. The teacher then explains the two types: specular and diffuse reflection, providing examples for each.
Pupils’ Activity: Pupils observe the demonstration, listen to the explanation, and identify examples of reflection in their daily lives.
Learning Point: Pupils learn about reflection and its types.

Step 4: Presentation of Refraction of Light

Time: 7 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher explains refraction as the bending of light and demonstrates it using a glass cup filled with water and a pencil. The teacher explains why light bends when passing through different media.
Pupils’ Activity: Pupils observe the demonstration and discuss their observations.
Learning Point: Pupils understand the concept of refraction and its effects.

Step 5: Presentation of Dispersion of Light

Time: 6 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher defines dispersion of light and demonstrates it using a prism and a torchlight (if available, or explains the phenomenon using diagrams). The teacher lists the colours of the spectrum.
Pupils’ Activity: Pupils observe the demonstration or diagram and note the colours of the spectrum.
Learning Point: Pupils learn about the dispersion of white light into its constituent colours.

Step 6: Class Activity/Experiment

Time: 8 minutes
Teaching Skill: Practical Application/Group Work
Teacher’s Activity: The teacher divides pupils into groups and provides each group with the instructional materials (mirror, glass cup, coloured paper). Pupils are instructed to experiment with light on these surfaces to observe absorption, reflection, and refraction. The teacher moves around to guide and assist.
Pupils’ Activity: Pupils actively participate in the experiments, observing and discussing their findings within their groups.
Learning Point: Pupils gain hands-on experience and reinforce their understanding of light properties.

Step 7: Evaluation/Review

Time: 5 minutes
Teaching Skill: Questioning/Assessment
Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

Define absorption of light.
State two types of reflection.
Explain what happens when light undergoes refraction.
Mention the phenomenon of light dispersion.

Pupils’ Activity: Pupils answer orally and in writing.
Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 5 minutes
Teaching Skill: Summarization/Assignment
Teacher’s Activity: The teacher summarises the key properties of light discussed (absorption, reflection, refraction, dispersion) and their relevance in photography. The teacher then gives an assignment.
Assignment: Research and write down five applications of reflection and refraction in everyday life or photography.
Pupils’ Activity: Pupils listen to the summary and copy the assignment.
Learning Point: Pupils consolidate their learning and prepare for further exploration of the topic.

Lesson Keywords

Absorption – The process of taking in light energy by a material.
Reflection – The bouncing back of light from a surface.
Refraction – The bending of light as it passes from one medium to another.
Dispersion – The splitting of white light into its constituent colours.
Spectrum – The band of colours produced when white light is dispersed.

Differentiation

For pupils who grasp concepts quickly, the teacher can challenge them to explain how cameras use the principles of reflection and refraction. For pupils needing more support, the teacher can provide simplified diagrams and allow more time for hands-on experimentation with direct guidance.

Note for teachers using this lesson plan

Ensure all instructional materials are available and in good working condition before the lesson. Encourage active participation during demonstrations and group activities. Emphasise practical applications of light properties, especially in the context of photography, to make the lesson more engaging and relevant.