Biology/Chemistry

Light and Vision

Objectives:

Explain Normal Eye

Define Refractive Error terms

Explain Refractive Errors

Demonstrate Refractive Corrections

Materials Needed:

The following materials are sufficient for a class of twenty.

1. 10 shoe boxes
2. 10 flashlights
3. 10 glass or plastic jars
4. 10 glass or plastic jars
5. 10 scalpels
6. 1 gallon various liquids (for example, water or vegetable oil)
7. 10 pencils
8. 20 eye diagrams

Strategy:

Introduction:

The teacher will demonstrate the construction of a shoe box experiment. To construct the shoe box experiment you would use the scalpel to cut two slits into the end of the box; the slits must be close enough for the light source to cover. Once this is done you would than place a jar of water or liquid in front of the light source.

• Draw two lines, two centimeters apart on one end of the shoebox
• Cut a narrow slit along each line
• Put the sheet of white paper in the bottom of the box
• Carefully put the jar full of water in the box. Make sure you line the jar up with two slits
• In a darkened room, shine the flashlight through the two slits. See how the jar of water or oil bends the light. You may need to move the jar to make the rays meet.

Performance Assessment:

• Identify the refractive error based on the location of liquid in the jar and its distance from the light source in the shoebox
• Write and/or verbally explain the following terms: myopia (nearsightedness), hypermetropia (farsightedness), and astigmatism (imperfect vision or image)
• Explain individually and cooperative groups how light affects vision
• Demonstration how refractive light can cause an astigmatism

References:

Ardley, Neil The Science Book of Light, Harcourt Brace Javanovich Pulbishers, 1991. Orlando, Florida.