Light and Color

Lesson Plan #: AELP-PHS0210

An Educator's Reference Desk Lesson Plan

Submitted by: Maria Vivirito
Email: mariavivirito@yahoo.com
Endorsed by: Bernard Poole
University of Pittsburgh at Johnstown

Date: January 29, 2003

Grade Level: 8

Subject(s):

Science/Physics

Duration: 50 minutes

Description: This lesson explores the colors of light and pigments by illustrating the use of the visible light spectrum in our everyday life. Students will be able to identify the relationship between color and light.

Goals: Pennsylvania Academic Standards for Science and Technology :

3.4. Physical Science, Chemistry and Physics
- 7.B. Relate energy sources and transfers to heat and temperature: Know that the sun is a major source of energy that emits wavelengths of visible light, infrared and ultraviolet radiation.

Objectives:

Students will be able to define opaque, transparent, and translucent and describe the differences between them.
Students will be able to describe how the different waves of light create color and why we are able to distinguish all the colors of the light spectrum.

Materials:

"shoebox of fun" (A shoebox with a eye-hole cut out of one end and a square cut out on the lid. Cover the hole on the lid with red cellophane. Inside the box glue down three gumballs -- red, green, and white.)
overhead projector
paper
pencils
Transparencies
Light and Color: Handout
Homework Assignment

Transparencies, Handout, and Homework Assignment in .pdf format; requires free Adobe Acrobat Reader.

Click the icon to obtain the free Reader.

Procedure:

Attention Getter: (5 min.)
Have students look into the "shoebox of fun." What do they see? Students write down their answers on a piece of paper and set aside.

Review: (5 min.)
Go over the previous class lesson (wavelengths). Write the spectrum on the board in order of decreasing wavelength (radio, infrared, visible light, ultraviolet, x- ray, Gamma rays).

Lecture: (10 min.)
Set up the scenario of waking up in a dark room. [ Author's Note: I simply tell the students a story about my morning routine of waking up in a dark room and then opening up my curtains to let in sunlight. I explain why I can't see anything until I let light in. This sets me up to talk about opaque, transparent, and translucent materials.] Different types of matter let in different types of light. Define the following:

opaque - Material that absorbs or reflects all light and you cannot see objects through them. (Example: curtains) Ask for another example!
transparent - Allows light to pass through and you can clearly see objects through them. (Ask the class for an example, such as a transparency!)
translucent - Allows light to pass through it but you cannot see objects clearly through it. (Example: frosted glass)

Transition:
"All matter has color. Do you think light has anything to do with color?" On the board, break down the light section into colors. "Light is made up of all the colors in the rainbow (ROY G BIV). There are three primary colors of light (make up all the other colors): red, green, and blue. Red + green + blue = white light. (Refer to the transparency on light, in Materials ). When we see a color, that means the object repels that color and absorbs all the other colors of the spectrum. So if something is white, what colors does it absorb? If we see light blue, what colors are absorbed? What about yellow and pink?"

Discussion: (5 min.)
Refer back to the box and have students hypothesize what is going on in the box, using the knowledge they now have. Refresh students' memories about what they saw in the box. Reveal what is inside the box. Have students hypothesize why the balls are not the colors that they saw with the lid on. "What kind of light was coming in the box with the lid on? With the lid off?" The lid acted as a filter. A filter is a transparent material that transmits one or more colors of light and absorbs all the other colors of the spectrum. "Why do you think the green balls looked black?"

Individual Exercise--Mixing of Colors: (at least 5 min.)
Place the primary color transparencies on the overhead. Have students take out a piece of paper. Ask, "Why does the mixing of the three colors give you black? What is happening to white light?" Students write their ideas on a piece of paper.

Discussion: (5 min.)
When everyone is finished, ask for a volunteer to answer the questions. Get several students' feedback. Define the term pigment : colored material that absorbs some colors and reflects others. Mixing of colors is used in our everyday life (Example: Sunday comics).

Handout: (10 min.)
Divide students into pairs and have them complete the "Light and Color" handout.

Conclusion: (5 min.)
Have students return to their seats. Ask for volunteers to share their answers to the questions on the handout. Go over any final questions that students may have.

Assignment:
Give students the homework sheet (see Materials ); it will be due the next class.

Assessment: Observe students' participation in activities and discussions. Collect students' handouts and homework assignments to check for accuracy and completeness.

Useful Internet Resource:
* Pennsylvania Academic Standards for Science and Technology
http://www.pde.state.pa.us/k12/lib/k12/scitech.pdf

Other Reference: Physical Science by Thompson, McLaughlin, and Smith; Glencoe/MacMillan McGraw Hill.