Detailed Lesson Note
Subject: Basic Science
Class: JSS 3 (Grade 9)
Topic: Light Energy
Week: Nine
Duration: 40 minutes
Date: To be inserted by the teacher
Sub-topics:
- Light as a form of energy
- Light ray
- Beam of light and its types
- Rectilinear propagation of light rays
- Reflection of light
- The pinhole camera
Instructional
Objectives
By the end of the lesson, students
should be able to:
- Define light as a form of energy. (Knowledge – Lower
domain)
- Explain the meaning of light ray with examples. (Comprehension
– Middle domain)
- Differentiate between the types of beams of light. (Analysis
– Higher domain)
- Demonstrate rectilinear propagation of light rays. (Application
– Higher domain)
- Analyze reflection of light using a plane mirror. (Evaluation
– Higher domain)
- Construct a simple pinhole camera and explain its
principle. (Synthesis – Higher domain)
Instructional
Materials
- Torchlight
- Cardboard with holes
- Plane mirror
- Drawing board, pins, and protractor
- Cardboard box (for pinhole camera)
- Candle
Previous
Knowledge
Students already know that we cannot
see in total darkness and that light from the sun and bulbs makes objects
visible.
Lesson
Development
Step
I: Introduction (5 minutes)
- Teacher asks: “Can you see inside a room when there
is no light at all?”
- Students respond: “No.”
- Teacher explains that this shows the importance of
light, which is a form of energy that enables us to see things.
- Teacher writes the topic “Light Energy” and
lesson objectives on the board.
Step
II: Presentation (25 minutes)
Objective 1 – Light as a form of
energy (5 minutes)
- Teacher explains: Light is a form of energy that
makes things visible and can be obtained from natural sources (sun, stars,
fire) and artificial sources (bulb, torchlight, candle).
- Teacher asks: “Give me two examples of sources of
light around you.”
- Students mention examples.
- Teacher emphasizes: Without light, we cannot see
objects clearly.
Objective 2 – Light ray (4 minutes)
- Teacher defines a light ray as the straight-line path
along which light travels.
- Teacher draws arrows on the board to represent rays.
- Students are asked: “Where have you seen rays of
light before?”
- Expected answers: Torchlight, sunlight passing
through windows, car headlights.
Objective 3 – Beam of light and its
types (4 minutes)
- Teacher defines beam of light as a group of light rays
traveling together.
- Teacher explains types with examples:
- Parallel beam
– rays move side by side (e.g., sunlight from a far distance).
- Convergent beam
– rays come together at a point (e.g., magnifying glass focusing
sunlight).
- Divergent beam
– rays spread out from a point (e.g., torchlight).
- Students are asked to differentiate between convergent
and divergent beams.
Objective 4 – Rectilinear propagation
of light rays (4 minutes)
- Teacher explains: Light travels in straight lines
unless obstructed.
- Teacher demonstrates with 3 cardboard pieces with
holes: when holes are aligned, light passes through; when one is shifted,
light is blocked.
- Students observe and describe what they see.
Objective 5 – Reflection of light (4
minutes)
- Teacher asks: “What happens when you look into a
mirror?”
- Students respond: “We see ourselves.”
- Teacher defines reflection: When light falls on a
surface and bounces back.
- Teacher demonstrates using a mirror and torchlight.
- Teacher states and explains the laws of reflection:
- The angle of incidence equals the angle of reflection.
- The incident ray, reflected ray, and normal all lie on
the same plane.
- Students draw a ray diagram of reflection.
Objective 6 – The pinhole camera (4
minutes)
- Teacher shows a simple pinhole camera made with
cardboard.
- Teacher places a candle in front, and students observe
the inverted image formed inside.
- Teacher explains: Light travels in straight lines,
and this causes the image to appear upside down.
- Students describe what they see inside the camera.
Step
III: Evaluation (5 minutes)
Teacher asks students the following
to assess learning:
- What is light?
- What is a ray of light?
- Mention the three types of light beams.
- Demonstrate that light travels in a straight line.
- State the two laws of reflection.
- Why does a pinhole camera produce an inverted image?
Step
IV: Conclusion (3 minutes)
- Teacher summarizes the lesson:
- Light is a form of energy.
- Light ray and beams of light.
- Light travels in straight lines.
- Reflection follows two laws.
- A pinhole camera forms inverted images.
- Teacher encourages students to observe how light
behaves in daily life.
Assignment
(2 minutes)
- Draw and label the diagram of a pinhole camera showing
an inverted image.
- Explain the difference between parallel and divergent
beams of light.
- State two natural and two artificial sources of light.
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