THE FACTS OF LIGHT
Grades 4-5

In this lesson and the use of its extending activities, the students should better understand light and its capabilities. Through the viewing of the recommended tapes and the hands-on activities of the guided experiments, they should have a better understanding that light is a wave that goes in a straight line unless it bumps into something. Should this happen, light can then either bend, bounce or be absorbed. This lesson would also be a good extension to the teaching of the five senses with the eye explicitly in mind and a further exploration into the colors of light and how we see them. This lesson also goes quite strongly with math concepts relating to finding patterns, multiples, filling in charts, and expressing information in the form of ratios, although this would take additional time should children not already have a background in ratios.

Bill Nye The Science Guy: Light Optics (KCTS/Seattle)
A Journey Through Your Eyes (cc) (American Optometric Association)
This video and curriculum guide may be obtained free of charge through American Optometric Association
243 North Lindbergh Blvd.
St Louis, MO 63141
Tel: 314-991-4100

Students will be able to:

• describe what three things can happen to light when it hits something;
• have a better understanding of how a kaleidoscope works;
• be able to measure distances from one image to an object;
• use a protractor to measure the angle of the hinged mirror and identify patterns with their relationship between the number of degrees and the number of images (angles that are proportional or multiples of each other).

"Find the Rainbow Colors"experiment

• a shallow bowl or pan
• water
• one sheet of silver plastic
• a white wall or cardboard
• a flashlight
• white paper
• a prism

"Bend Light With Water" (One supply for the class)

• a clear drinking glass
• water
• a pencil

"The Coin Illusion" (one supply for each group of four to six)

• an opaque (not clear) bowl
• transparent tape
• a coin

"Checking All The Angles" (per group of two-four students)

• a book
• a sheet of white paper
• a comb
• a flashlight
• a darkened room
• one sheet of silver plastic
• a friend or helper
• a pencil or pen
• a ruler
• a protractor

"Make a Kaleidoscope"

• 3 sheets 1"-by-4" card stock backed with silver mylar
• transparent tape
• 3/4 ounce plastic portion cup
• brightly colored clear plastic beads
• toilet paper tube
• 2 pieces of paper towel

light - electromagnetic radiation that can be seen by the naked eye

light spectrum - a name given to the rainbow colors found in white light

reflection - bouncing back of a light beam or a sound wave

refraction - the bending of a light ray that occurs when it passes through certain substances

internal reflection - reflection inside something

focal point - the point where light rays intersect

concave - hollow and curved inward (like a cave)

convex - curved outward like the outer surface of a ball

Start by talking about light itself. What is light? White light that comes from the sun and from ordinary light bulbs is called white light. But did you know that white light really isn't white? White light is a mixture of every color of the rainbow. The children should be able to recall what the colors of the rainbow are but if not sure of the order, tell them to try to remember the name Roy G. Biv. This name comes from the first letter of each color of the rainbow: Red, Orange, Yellow, Green, Blue, Indigo, and Violet.

Prove this by doing the experiment "Find the Rainbow Colors." Fill the bowl or pan with water. Put it in a sunny sport of near a source of bright light such as a lamp, sunny window or flashlight. Hold the silver plastic in the water so that it faces the light source. The white wall or cardboard should be opposite the silver plastic. Adjust the silver plastic until you can see a colorful spot on the wall or cardboard. You will see tiny bands of colors: red, orange, yellow, green, blue, indigo and violet. These colors are called the rainbow or light spectrum. Explain that the water bends each color of light differently so when the light reaches the white wall, it is no longer mixed into white light. It is separated into different colored bands.

Emphasize this by letting the sun or flashlight beam shine directly through the largest side of a prism onto the white paper. Adjust the prism by tipping it up and down a bit. When the prism is at the right angle, you will see the rainbow or light spectrum on your paper. Ask if these colors came as the ones you saw in the first activity? Are they in the same order? Did they see Roy G. Biv?

To give the students a specific responsibility while viewing say, "You are now going to view Bill Nye The Science Guy: Light Optics. You will be able to take the information you just learned about the eye and 'Roy G. Biv' and combine it with additional information on light and how it travels, what changes the way it travels, and how we can change light's beam at times. After watching this part of the video we will be learning about how the eye works and how it relates to light. We will also be working with mirrors and discovering what makes the images change."

Note to the Teacher: This lesson can easily be broken into two or even three parts. The first is the basics of light, the second would be the eye itself and how it works, and the third could be refraction, reflection and mirrors with their activities.

START the video Bill Nye The Science Guy: Light Optics after the credits to where the two men introduce themselves saying, "Hi, I'm Penn and this is Teller..." PAUSE the video and discuss what was meant by using the names "Penn" and "Teller." RESUME the video and continue until after the second light bulb where the girl says, "light travels in a straight line unless it hits something or is pulled by gravity." PAUSE and review what happens to light when it runs into something. Tell the children that they will now see examples of reflection and learn what a focal point is. RESUME the tape at the two words "reflection" and "refraction". They will watch examples of large dishes used for outer space and discover how remote controls work for televisions. PAUSE where both children are arguing over the remote control, saying, "channel 9, channel 11." Discuss the difference between the white paper and the black paper. Why doesn't the black paper work? RESUME at the word "refraction," where Bill Nye says, "This magnifying glass is making my eye big. Why is that?" Continue until they are showing light going through a curved lens and the word "focal point" appears. STOP the video. Discuss what happens to light as it passes through something clear like plastic. Ask them if they could think of anything else that light might be able to pass through? Ask them what the round plastic reminds them of. Wait or encourage the idea of eye glasses.

Note to teacher: This is a good stopping point if the lesson is too long for a class period.

Now tell the children that this lesson will be investigating how the eye works and how it is related to light. Tell them that they will be watching another video on the human eye.

START the video A Journey Through Your Eyes at the beginning. PAUSE where the narrator is saying, "this entire process is called vision." There is a profile of an eye with an airplane image. Go over the eye model and review the parts of the eye. Resume where the narrator is saying, "Now that you understand how vision works, let's look at some things that can be problems to the eye." Watch as they discuss farsightedness, nearsightedness and astigmatism. STOP after the study of astigmatism where there are colorful flowers and the narrator is saying "this will allow you to see clearly at all distances." Have a discussion and review of the different parts of the eye, the three major problems of the eye and how certain kinds of lenses can correct these problems by the way that light goes through the lens.

Go back to the video Bill Nye The Science Guy: Light Optics . Review what a focal point is and readdress the question of why Bill Nye's eye was larger when holding the magnifying glass up to his eye. REWIND to the words "Refraction and Reflection," just after the two children are arguing over the television channels. Bill Nye is saying, "This magnifying glass is making my eye look big. Why is that?" Now say to the children, "Now that you have a better understanding of how the eye works, I would like to show you the segment about the magnifying glass again. This time I would like you to think about why your eye looks large when it is seen through a magnifying glass." RESUME the video to review the different things light can do. STOP at the end of the segment before credits.

Reinforce the information shown in the tape by doing the three experiments that represent light bouncing, bending and reflect. As you finish each one, discuss how each experiment demonstrates what light is doing. Once this is done, talk about how light is absorbed, for example, with black paper or the greenhouse.

Bouncing Light: When you bounce a ball straight down, it travels straight up again. But if you bounce a ball away from you, it hits the ground at an angle. It bounces away from the ground at the same angle. Light can also bounce from a surface at an angle.

Find out about the Angle of Light reflection with the following experiment.
Checking All the Angles: Place the white paper over the book. Hold the comb so that the teeth raise above the edge of the book. Darken the room and turn on the flashlight. Direct the light at the comb and book. Tilt the book so that long rays of light can be seen on the surface of the paper. Now hold the silver plastic upright on the paper. You will see reflected bars of light crossing the original bars.
Keeping the silver plastic upright, move it so that the bars of light hit it at different angles. What happens to the reflected bars of light? What patterns can you make with these bars of light? Use a ruler to draw a diagonal line across the white paper. Hold the silver plastic up to the line. Have a helper trace on the bar of light coming from the flashlight. Then have the helper trace the same bar of light as it reflects off the silver plastic. Turn on the lights and look at the paper. Look at the angles made by the bars of light and the silver plastic. Is the angle made by the bar of light coming from the flashlight the same as the angle made by the reflected bar? You may want to use a protractor to be sure.

Bend Light With Water: Normally light travels in straight lines. It does not turn corners. But now you will discover that light does bend sometimes, after all! Put the pencil in a glass of water so that it is at a slant. Look at the pencil through the top of the glass. Does it bend? Why do you suppose it looks this way? Look at the pencil through the side of the glass. How does it look? (internal refraction) Now hold the pencil straight up and down in the water. Again look at it through the top and side of the glass. Does the pencil look bent? Try the same experiment with a drinking straw or butter knife.

Coin Illusion: Tape a coin to the bottom of a bowl. Now sit so that the coin is just out of your view behind the rim of the bowl. Sit very still while another person slowly pours water into the bowl. Does the coin reappear? Why?

Note to the teacher: Without any water in the bowl, the light that reflects off the coin travels in a straight line, missing your eyes. However, when water is in the bowl, the light refracts, or changes direction. When the light changes direction you can see the coin.


Have an optometrist come to visit the class and explain about the different kinds of eye disorders, the different lenses used to correct them, and the major eye diseases and injuries to the eye.

Have an optomologist come to the class to talk about the new surgery that can be done on people's eyes that will change the shape of their eye and therefore correct their vision.

Invite other surgeons to come to the class to talk about all the micro surgeries performed today and how exactly they are performed. It might also be possible to go to a local hospital and see the equipment directly.

Visit a green house and talk about how it functions effectively.

Math: Do additional work with protractors and taking accurate measurements of different sized angles under 180 degrees. Practice enough so that children can recognize obtuse from acute and can also recognize a 90 degree angle.

Science and Math: Do an activity placing a folding mirror on previously drawn lines that are at specific sized angles. Then hold an object or picture in front of folding mirrors. Predict how many images can be seen all together at the different set angles. Then actually count.

Social Studies and Writing: Have the students look up Albert Einstein to find out more about what his part in history was. Write a report to present to the class on your findings.

Art and Science: Make a periscope by using mirrors and a quart-size milk or juice container.

End your entire unit on light by having the children make a kaleidoscope to take home. It is a great keepsake and a reminder of light and how they see all that they see. (See attached instruction sheet.)

Master Teacher: Gail Roberts