SummaryIn a hands-on way, students explore light's properties of absorption, reflection, transmission and refraction through various experimental stations within the classroom. To understand absorption, reflection and transmission, they shine flashlights on a number of provided objects. To understand refraction, students create indoor rainbows. An understanding of the fundamental properties of light is essential to designing an invisible laser security system, the ongoing objective in this unit.
In designing laser-based security systems, engineers consider the implications of the penetrating properties of electromagnetic radiation. The concepts of wave absorption and transmission are fundamental in the design of laser based security systems, and have additional applications in biomedical engineering. In x-ray imaging, various tissue types result in a range of transmittances that can be recorded to depict bones on x-ray film. Engineers must also be aware of safety concerns; even low doses of high-energy radiation can be dangerous, especially in the case of gamma radiation. For cancer radiation treatments, control of high-energy radiation can be beneficial, but must be carefully managed. Students consider the potential real-world uses of various types of radiation in questions 2 and 5-9 of the post-activity assessment handout.
A basic understanding of light properties as presented in lesson 2, Learning Light's Properties.
After this activity, students should be able to:
- Explain the properties of light as related to security systems.
- Describe which objects reflect, absorb or transmit light.
- Explain light refraction as applied to rainbows that appear in nature.
- Identify a number of applications of radiation to science and technology today.
This activity also meets the following Tennessee Foundations of Technology educational technology content standards: 2.0, 3.0, 4.0, 5.0, 6.0, 7.0 and 8.0.
This activity also meets the following National Science Education Standards (NSES) teaching standards: A, B, C, D, E, F; see http://www.nap.edu/readingroom/books/nses/
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Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.
All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).
In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.
- Perform operations with numbers expressed in scientific notation, including problems where both decimal and scientific notation are used. Use scientific notation and choose units of appropriate size for measurements of very large or very small quantities (e.g., use millimeters per year for seafloor spreading). Interpret scientific notation that has been generated by technology. (Grade 8) Details... View more aligned curriculum... Do you agree with this alignment? Thanks for your feedback!
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- Exploring Light Properties! Worksheet, one per person
- What have you learned today? Handout, one per person
Station 1: Making Rainbows (Consider making several of these stations, depending on class size.)
- glass bell jar filled with water
- small, compact mirror
- LED flashlight
- aluminum foil
- plastic wrap
- wax paper
- LED flashlight
- finger or hand
- LED flashlight
- tissue paper, various colors
- notebook paper
- LED flashlight
For teacher use:
- printout(s) of the Electromagnetic Spectrum Visual Aid
Today's activity brings a little fun and excitement to the concepts we have recently learned. The purpose of today's hands-on exploration is to reinforce your understanding of how different materials respond to a beam of light. We will explore light absorption, transmission, reflection and refraction. To explore refraction, you will create your own rainbow in the classroom. For the activity, you will spend 15 minutes at each of four stations set up throughout the classroom, answering questions and recording your predictions and observations on a worksheet.
With an understanding of the properties explored in this activity and an understanding of lasers gained in a future lesson and activity, you will be able to design your invisible laser security system to protect our mummified troll.
absorptance: The ratio of the amount of radiation absorbed by a surface to the amount of radiation incident upon it.
absorption: The removal of energy or particles from a beam by the medium through which the beam propagates.
opaque: Impenetrable by light, resulting in complete reflection.
reflectance: The ratio of the intensity of reflected radiation to that of the radiation incident upon the surface.
reflection: The return of light, heat or sound after striking a surface.
refraction: The change of direction of a ray of light, heat or sound in passing from one medium into another in which its wave velocity is different.
transmittance: The ratio of the radiation transmitted through and emerging from a body to the total radiation incident on it. Also equivalent to one minus the absorptance.
transparent: Having the property of transmitting rays of light through its substance.
This activity provides students with a hands-on means of exploring the light properties of reflection, absorption, transmission and refraction.
Before the Activity
- Gather materials and make copies of the attached Exploring Light Properties!Worksheet and What have you learned today? Handout, one each per student.
- Tip: Once you gather the materials to do this activity with your students, go through the activity first yourself. That way, you can fill in the results for the worksheet chart, based on the exact materials and light source (flash light) that your students will be using, essentially creating your own answer key.
- Set up the stations as described in the Materials List section. Set up station 1 in the darkest area of the room. Depending on class size, more than one station 1 may be helpful.
- Divide the class into groups of three students each for exploring each station; assign each group to a starting station.
With the Students
- Hand out the worksheets.
- For station 1: Direct student teams to follow the instructions on their worksheets and record both their predictions and observations.
- For station 2-4: Direct student teams to fill out their worksheets by first predicting whether the light will be absorbed, transmitted or reflected, as well as the color of the resultant light. Then experiment to find the results and record their observations.
- Lead a class discussion in which students share and compare their results and conclusions. See the Assessment section for a description of typical results.
- To conclude, have students individually complete the handout.
- Considering our objective to protect our mummified troll, how could light absorption, reflection or transmission apply?
- If we shine a light forward and you walk in front of it, it suddenly disappears. What is happening?
- How can we use this concept to protect the troll?
- What type of sensor would we need to detect the presence of a burglar?
- Where would the light from a flashlight fall on the electromagnetic spectrum?
- What happens if we used a different type of energy along the electromagnetic spectrum?
- What else must we consider for safety constraints?
Activity Embedded Assessment
Worksheet & Discussion: As students go through the stations, have them complete the worksheet chart with their predictions and results. In a class discussion, have students share and compare their results and conclusions. Results will vary, depending on the exact materials and light sources used, but in general, expect:
- reflective materials, such as aluminum foil and the mirror, to reflect the light
- solid, non-transparent materials, such as wax paper, body parts, notebook paper and cardboard paper, to absorb the light
- materials that have varying degrees of transparency, such as plastic saran wrap and tissue paper, to transmit the light
- the lighter colored tissue paper to most likely transmit more light than the darker colored tissue paper
- materials such as cheeks and notebook paper to transmit some light, although most likely absorbing most of the light
Concluding Handout: After the activity, have students return to their desks and individually complete the What have you learned today? Handout. This assessment contains both content questions and application questions in which students consider applications to designing a security system.
Direct students with unanswered questions to explore the internet for further answers.
Loan flashlights to students who are interested to explore shining the laser light on other objects at home.
Suggest that students show their families the indoor rainbow, as described at the Indoor Rainbow at Weather Wiz Kids at: http://www.weatherwizkids.com/rainbow1.htm
- For lower grades, introduce group discussions exploring objects as a class. Also complete the indoor rainbow demonstration as a class, instead of in small groups.
- For upper grades, ask further investigating questions with respect to laser security systems and what types of lasers students suspect to be the most appropriate. Also ask additional investigating questions on the application of laser technology to medicine.
Dictionary.com. Lexico Publishing Group, LLC. Accessed December 29, 2008. (Source of vocabulary definitions, with some adaptation)
Copyright© 2013 by Regents of the University of Colorado; original © 2008 Vanderbilt University
Supporting ProgramVU Bioengineering RET Program, School of Engineering, Vanderbilt University
The contents of this digital library curriculum were developed under National Science Foundation RET grant nos. 0338092 and 0742871. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.
Last modified: March 2, 2018