Unit 15 Light, Colours and Beyond

Topic

How do our eyes work?

Curriculum Link

11.2 How we see: functions of main parts of the eye
11.9 The brain and our senses: interpretation of signals
15.1 How we see an object: non-luminous objects are seen because light reflected from them enters our eyes
15.2 Reflection at plane surfaces: law of reflection

Estimated Lesson Time

80 minutes

Introduction

In this activity, students will learn and apply the parts of eyes in the daily-life examples. It is recommended to first let students know the structures of eyes by dissection of ox eyes before this activity.

Key Question

How do our eyes work?

Learning Objectives

In this activity, the students should be able to

  1. describe how image is formed and draw ray diagram to represent the path of light (SP 1); 
  2. apply the basic concepts of light reflection and refraction and draw ray diagram to represent the path of light entering the eye ball;
  3. describe how different parts of eyes and the brain coordinate for human vision;
  4. describe the location of blind spot through hands-on activity (SP 5);
  5. identify three types of cones cells;
  6. explain different eye diseases based on their learning in this activity.

Teaching Plan

Task (Time) Brief Description Materials Objectives

Exploration
(15 min)
  • Students explore the working principles of image formation. Teacher is recommended to ensure a sharp image can be formed for demonstration.
  • Teacher introduces the concepts of the focusing power of lens and light refraction.
(1)

Explanation
(30 min)
  • Students apply the concepts of reflection and refraction in order to draw the ray diagram.
  • Students explain how human can perceive an object with reference to the basic parts of eyes (cornea, pupil, lens and yellow spots).
  • Teacher can bring convex lens to show the focusing power of lens and eye model for the path of light ray
 (2) & (3)

Engagement & Explanation
(15 min)
  • Students are engaged to a hands-on activity for the disappearance of object.
  • Students explained the location of blind spot based on their observation in the activity.
(4)

Exploration & Explanation
(10 min)
  • Teacher shows a green cross by projecting it on a white screen and engages students to stare at it for one minute. After that, teacher turns to a white screen.

  • Students explain the perception of purple cross on the white screen.
  • Teacher can replace the green cross with the blue and red crosses to consolidate students' understanding about the three types of cones.

(5)
Exploration & Evaluation
(10 min)
  • Students elaborate what they have learnt about the eyes to explain different the effects of different diseases.
  • Teacher evaluates students' application of concepts learnt on the diseases.
(6)

*Apparatus and materials required: