Italicized font represents information to be shared orally or physically completed with the students at this time.

The non-italicized font represents additional information included to support the teacher’s understanding of the content being introduced within the CELL.

ASK WHY

Remind students that light is all around us. It has the ability to tan or burn our skin. It can be harnessed to melt metals, create electricity, and heat our food. It gives us sight, color, warmth, and enables gadgets like computers, cameras, televisions, traffic lights, mirrors, eyeglasses, and microscopes to function.

BRANCH OUT

Remind students that forensic scientists use black lights to analyze crime scenes. To pick out fingerprints, for example, they often dust with fluorescent dye under a black light. This makes it easier to pick the fingerprints out from surrounding dirt.

GET FOCUSED

GO DEEPER

As a class, read the Background(s) in the Investigation. Have students read the information aloud or silently to themselves. When students have finished, discuss the following concepts as a class:

• An absorbance spectrum shows how different wavelengths of light are absorbed by a substance.
• Some transparent materials, such as clear window glass, are transparent to all wavelengths of visible light.
• Other transparent materials are transparent to only certain wavelengths of visible light. For example, the red glass of a traffic light appears red because the pigments in the glass absorb all the wavelengths of visible light except those around 700 nm (red). This wavelength is transmitted and you see red light.
• Wavelengths of light are absorbed and reflected by different colored opaque objects.
• This concept can be easily demonstrated using filters. Each filter only allows a particular wavelength of light to pass through it. The color of the filter indicates the wavelength that passes through it. For example, the red filter only permits red wavelengths of light to pass through it, not green or blue wavelengths of light.

Note: These concepts are integrated into the Background(s) and are used to deepen students’ comprehension of the big ideas.

LEARN THE LabLearner LINGO

The following list includes Key Terms that are introduced in the Investigation Background(s). They should be used, as appropriate, by teachers and students during everyday classroom discourse.

• transparent
• opaque

Note: Definitions to these terms can be found on the Introduction page to the CELL.

Note: Additional words may be bolded within the Background(s). These words are not Key Terms and are strictly emphasized for exposure at this time.

SET FOR SUCCESS

• Direct students to complete the Recall section in their SDRs. Student answers may vary.
  • Can you tell when light wavelengths will be absorbed or transmitted by objects?
  • What kind of objects absorb light?
  • What kinds of objects transmit light?

• Explain to students that during this Investigation, they will investigate the relationship between light and the color of transparent substances.
• Play the video below. Stop to ask students questions or answer students’ questions when necessary. Remind students to follow along with their SDRs and make any notes that they think might be helpful.
• After the video, direct students to divide into their lab groups to discuss their strategy for the lab. For example, they may assign certain group members to perform specific functions during the lab.

Note: The purpose of the video is to allow students to anticipate the laboratory experience they will soon encounter. Students should leave this PreLab session with a firm idea of what to expect and how to perform in the lab.

Note: Homework is posted below the video.

HOMEWORK

Tell students that they should review the Investigation in preparation for the Lab.