Total Time: 30 - 45 minutes
Audience: Middle School Science Teachers
Education Level: Grades 5 - 9
Content Area: Waves
Educational Topic: Waves, features of waves, wave terminology
Objectives: Students will be introduced to how multiplexing works and combine what they’ve learned about waves to make an educated guess as to how multiplexed signals are eventually separated out.
Key Question: How does using different wavelengths of light allow multiple messages to be sent in a single channel at the same time?
MS-PS4-2. Develop and use a model to describe how waves are reflected, absorbed, or transmitted through various materials.
CCC: Influence of Science, Engineering, and Technology on Society and the Natural World ▪ Technologies extend the measurement, exploration, modeling, and computational capacity of scientific investigations. (MS-PS4-3)
CCC: Science is a Human Endeavor ▪ Advances in technology influence the progress of science and science has influenced advances in technology. (MS-PS4-3)
SEPs: Scientific Knowledge is Based on Empirical Evidence ▪ Scientific knowledge is based upon logical and conceptual connections between evidence and explanations. (MS-PS4-1)
Overview: Students start by exploring with the 3D glasses and markers/colored pencils/crayons to find colors that work well for this activity. It’s important to use markers, highlighters, or colored pencils that are tuned to the wavelength of light that each filter transmits.
The right color will “disappear” when viewed through the 3D glasses. Then, students can create “multiplexed messages” — making overlapping letters/numbers with different colors allows you to transmit two different messages on top of each other; you can see one message with the red lens in the 3D glasses, and the other message with the cyan lens. Then students are asked to review what they’ve learned so far and think about how they could separate laser light multiplexed messages in a fiber optic cable.
Watch this video from Little Shop of Physics for an overview of the experimental setup and the science behind the phenomenon!
The 3D glasses in the kit each have one red lens and one cyan lens. Red and cyan are complementary colors; red transmits the long-wavelength end of the visible light spectrum, and cyan, the short-wavelength end of the spectrum. Some colors can be seen through one lens but not through the other. The glasses create a 3D effect when two slightly different versions of a given image are printed on the same piece of paper — one version of the image is visible through the red lens, and the other version is visible through the cyan lens. You can make a 3D picture of your class using a free app! (See Assessment/Extension Activities Section for more information!)
But you can also use this property of the glasses to make what we call “multiplexed messages” — two overlying messages or pictures on the same paper.
Students will be introduced to how multiplexing works and combine what they’ve learned about waves to make an educated guess as to how multiplexed signals are eventually separated out.*
*It is important to understand that student goals may be different and unique from the lesson goals. We recommend leaving room for students to set their own goals for each activity.
Watch this video from Little Shop of Physics for an overview of the experimental setup and the science behind the phenomenon!
Multiplexing is a key innovation in communication technology. When signals are multiplexed, they’re layered over one another in a single channel but are encoded using different wavelengths and so can be separately decoded by devices. This activity is an introduction to what it means to multiplex messages.
Objective: Students will be introduced to how multiplexing works and combine what they’ve learned about waves to make an educated guess as to how multiplexed signals are eventually separated out.
Students: After reading the introduction, what is your essential question or objective for this activity?
**Real-world situations/connections can be used as is, or changed to better fit a student’s own community and cultural context.
Created by Cherie Bornhorst, MEd, and Little Shop of Physics (INSERT LOGO from LSOP and CSU) along with Nicole Schrode, MEd, and Claudia Fracchiolla, PhD, of APS Public Engagement
Reviewed by Summer Chrisman, MEd, Tamia Williams, MSt, Chris Irwin
Extensions by Jenna Tempkin
Formatted by Sierra Crandell, MEd, partially funded by Eucalyptus Foundation
PhysicsQuest © 2023 by American Physical Society is licensed under CC BY-NC 4.0