What Makes White Light and Primary Colors of Light Lesson Plan


Name : Susan Schepp Date: 11/14/96
Subject Area: Science Grade Level: 3-4

1. Instructional Objectives: Students will learn the concept of primary colors of light. When the primary colors of light are all combined together they make white light. Primary colors of light are different than primary colors of pigments.

2. Materials: Three flashlights or three slide projectors, red, green and blue plastic sheets.

3. Anticipatory Set: When colors are seen on a computer screen and on television, does anyone wonder what is used to produce the different colors we see? These colored images are produced by using the primary colors of light, as opposed to using the primary colors of pigments, which produce the colored images we see in photographs and printing. Today we are going to experiment with the primary colors of light. We will make some predictions about which combinations of the primary colors of light will produce different colors.

4. Activities: We will use three flashlight and a square of blue, red and green plastic. First we will attach a different colored circle of plastic sheet to each flashlight. Three students will position the beam from each flashlight to form the pattern I drew on the chalkboard. I would like all of you to copy this pattern in your observation journals and write predictions about what colors will appear in the overlapping circles. The colors red, blue and green are the "primary" colors of light.

Results


5. Modeling of Activities: The teacher attaches the different colored plastic strips to the flashlights. Teacher picks out three students to hold the flashlights. The lights are turned down. The teacher helps to guide the students to shine the lights on a white screen or white part of the wall to form the above pattern.

6. Guided Practice: As students take turns shining the flashlights onto the wall the teacher asks the students to determine what colors appear in the overlapping parts of the circles. What color does red and green make? Students should mark on their papers the colors that are formed.

7. Checking For Understanding: Have students compare and discuss their predictions and results. What makes up white light? (all the primary and secondary colors) If red, blue, and green are the primary colors of light what are the secondary colors of light? (yellow, blue-green and magenta) Are the primary colors of light different than the primary colors of paint? If so, why? (Yes. The primary colors of pigments relate to the absorption and reflection of light waves. The primary colors of light relate to the mixing of actual light waves)

8. Independent Practice: When you go home today take a close look at your TV screen (a magnifying glass may help). See if you can see what colors make up the dots on the screen. Bring your findings to class tomorrow.

9. Closure: Today we have investigated the primary colors of light. Perhaps we can have a greater understanding about what makes up the colors we see on the TV screen and computer screen. We now know that a different process is happening to determine what colors we see on TV versus photographic or printed images. Does anyone have any questions or comments they would like to share with the class?

10. Evaluation: Review the students journals to see if they colored or marked in the correct colors. Ask students whether their predictions where correct. Ask students to write in their own words the difference between the primary colors of light and the primary colors of pigments and what makes them different.

11. References :
Jurca, M, E (1992). Physical Science : Light Solids, Liquids & Gases Energy. Torrance, Calif: Frank Schaffer Publications, Inc.
Siepak, K, L (1994). Light & Color: Bending and Reflecting Light Shadows Color Pigments Eyes and Visual Tricks. Greensboro, NC.: Carson-Dellosa Publishing Company, Inc.
Kepler, L (1996). Teach Kids How Light Works By Making Rainbows. Instructor, 106 (1), 76, 85-86.
VanCleave, J (1991). Physics For Every Kid: 101 Easy Experiments in Motion, Heat, Light, Machines, and Sound. New York : John Wiley & Sons, Inc.
Levenson, E (1994). Teaching Children about Physical Science. TAB books, a division of McGraw-Hill, Inc.
Ardley, N (1991). The Science Book Of Color. London: Gulliver Books, Harcourt Brace & Company.