Visible light can be produced by incandescence or luminescence. Incandescence is the production of light by an object that is so hot it glows. Luminescence is the production of light by other means, such as chemical reactions. Light may interact with matter in several ways, including reflection, refraction, transmission, and absorption. Matter can be classified on the basis of how light interacts with it as transparent, translucent, or opaque. The wavelength of visible light determines the color that the light appears to the human eye. The primary colors of light are red, green, and blue. All other colors of light can be created by combining these primary colors.
- MCR.6-8.SCI.9.8, 9
- AAAS.6-8.4.D.15; AAAS.6-8.4.E.5; AAAS.6-8.4.F.1, 6, 7, 8
- Identify common sources of visible light.
- Explain how light interacts with matter.
- Describes the colors of visible light.
absorption: interaction of light with matter in which the particles of matter absorb light energy so light neither reflects from nor passes through matter
incandescence: production of visible light by an object that is so hot it glows
luminescence: production of visible light that does not involve high temperatures but instead occurs through chemical reactions or other means
opaque: referring to matter that does not allow visible light to pass through it because it reflects or absorbs all of the light
pigment: substance that colors materials by reflecting light of certain wavelengths and absorbing light of all other wavelengths
primary color: one of three colors (red, green, or blue) that can be combined to produce all other colors of light
scattering: process in which transmitted light is spread out in all directions by particles of matter
translucent: referring to matter that transmits but scatters visible light
transmission: process in which light passes through matter
transparent: referring to matter that allows all visible light to pass through
Introducing the Lesson
Use a prism to make a rainbow on a sheet of white paper or overhead projector. Ask students to identify and explain what they are seeing. Accept all reasonable answers at this point, and tell students they can find the correct answers when they read this lesson.
You may want to use the online lesson at the following URL to teach the topics in the FlexBook® lesson. The online lesson focuses on the idea that we can see objects because they either emit or reflect light. It discusses the way light is reflected, absorbed, and scattered to allow certain wavelengths to reach the eye, leading to the perception of different colors. Materials include a student worksheet, slideshow, and hands-on activity in which students examine different materials and describe how they interact with light.
Building Science Blocks
You can use the NASA-created lesson plan at the URL below to introduce students to the basics of the primary additive colors. They will learn about the primary colors and color addition through a hands-on experiment with flashlights and colored filters. The Web site includes printable worksheets with answer keys.
Pair students of differing abilities, and ask partners to make flashcards of the lesson vocabulary terms. Tell them to write each term on one side of an index card and a definition and example on the other side of the card. Have pairs exchange flashcards and then use them to quiz their partner on the terms.
Students with an interest in life science may enjoy learning more about bioluminescence. Suggest that they identify at least two or three additional organisms (besides jellyfish and fireflies) that are bioluminescent and find out how they make use of their ability to produce light (some examples are described at the URLs below). Ask the students to prepare a PowerPoint presentation on the organisms to share the information with the class. Tell them to include photos of the organisms in their presentation.
In the inquiry activity at the URL below, students work cooperatively to learn how light refracts through a prism. An accompanying Java simulation allows them to explore the refraction of light as it moves from a vacuum to different media, including air, water, and glass. Also included are details about Isaac Newton's early work with prisms.
Use the worksheet/assessment at the first URL below with the PhET simulation “Color Vision” at the second URL. The worksheet gives step-by-step directions to focus students on the fundamentals of color addition and subtraction, with opportunities to construct hypotheses as they go.
Electromagnetic radiation is sometimes referred to simply as “light.” For example, the speed of all electromagnetic waves is often called simply the “speed of light.” However, as discussed in this chapter, light refers specifically to visible light, which is just a tiny part of the electromagnetic spectrum. These dual uses of the term light may lead to confusion. Students may also confuse the spectrum of colors of visible light with the electromagnetic spectrum. Discuss these possible areas of confusion with the class to avoid misconceptions.
Reinforce and Review
Copy and distribute the lesson worksheets in the CK-12 Physical Science for Middle School Workbook. Ask students to complete the worksheets alone or in pairs to reinforce lesson content.
Lesson Review Questions
Have students answer the Review Questions listed at the end of the lesson in the FlexBook® student edition.
Check students’ mastery of the lesson with Lesson 22.1 Quiz in CK-12 Physical Science for Middle School Quizzes and Tests.
Points to Consider
In this lesson, you were introduced to the reflection and refraction of light. The next lesson “Optics” describes how mirrors reflect light and how lenses refract light.
- Based on your own experiences with mirrors, how do you think a mirror forms an image of the person in front of it?
- An example of a lens is a hand lens, also called a magnifying glass. This type of lens makes objects look bigger than they really are. How do you think this happens?