Hands-on Activity: Light Scavengers

Contributed by: Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder

An illustration of a star shown in three ways indicating opacity, translucency and transparency.
Students investigate how light interacts with objects
Copyright © http://upload.wikimedia.org/wikipedia/commons/thumb/1/1b/Opacity_Translucency_Transparency.svg/2000px-Opacity_Translucency_Transparency.svg.png


Students examine various materials to investigate how they interact with light. They use five characteristics—translucency, transparency, opaqueness, reflectivity and refractivity—to describe how light interacts with the objects.

Engineering Connection

Engineers care about light! Lighting engineers design ways to illuminate public and private spaces. Engineers also work to create new types of light fixtures and light bulbs, including some that are more energy efficient. In order to design illumination systems and create new devices, engineers must understand the properties of light and how it interacts with various materials.

Pre-Req Knowledge

Students should be comfortable with the material covered in lessons 1-6 of the Sound and Light unit.

Learning Objectives

After this activity students should be able to:

  • Investigate how light interacts with an object.
  • Describe whether a given object is transparent, translucent or opaque.
  • Determine if light is reflected, refracted or goes directly through an object.

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Educational Standards

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.

Suggest an alignment not listed above

Materials List

Each group needs:

To share with the entire class:

  • books, several
  • 1-2+ hand mirrors
  • 1-2+ magnifying glasses
  • 1-2+ clear glasses of water with a pencil in it
  • 3-4 empty glasses
  • wax paper, several sheets


Now that we have talked about our five important light vocabulary words, you have a chance to work together to investigate some objects and see how they interact with light! First, we need to come up with an easy way to remember what all of our new words mean. Let's write the words on the board and see if we can come up with some clear definitions. (Write the following words on the white/chalk board: transparent, translucent, opaque, reflection, refraction)

Can you think of short definitions for each word? (Ask students to raise their hands to answer. If students are struggling, work with them to create simple definitions and write them on the board next to the words. Remind them to check the board for these definitions if they are not sure during the activity. Some ideas are: transparent means clear; translucent means a little harder to see through; opaque means you cannot see through it at all. And, reflection means the light comes back towards me; refraction means the light is bent inside the object.)

Great job, everyone! Now that we all understand what our new vocabulary words mean, I am going to divide the class into groups of two and give you a chance to investigate 10 different objects. Eight of them are listed on your worksheet, and the last two you can choose yourselves.

Okay, we're almost ready to get started, but I just have one question for you: What does light have to do with engineering? (Answer: See Pre-Activity Assessment.) Let's think about it for a minute and see what we decide. Who would like to share their answer? Great! You are right – lighting engineers design lighting for spaces, including small rooms and big concert halls. Other engineers design new types of light fixtures, including some that are more energy efficient, which means they use less energy. Now that you know more about engineering, let's get started!


opaque: None of the light goes through; it is either reflected or absorbed.

reflection: The direction of light is changed; it is as if it bounces from the surface.

refraction: The tendency of a light wave to bend as it passes from one transparent medium to another.

translucent: Lets some of the light through; gives off a diffuse glow (not as image preserving as transparent glass).

transparent: Lets most of the light through; images are preserved.



The objective of this activity is for students to investigate different materials to see if they are translucent, transparent or opaque, and if they reflect, refract or transmit light. The "My Notes" section of the Light Scavengers worksheet is for students to state any additional observations or questions they have about each object.

Before the Activity

  • Gather materials.
  • Make copes of the Light Scavenger Worksheet, one per group.

With the Students

  1. As a class, come up with easy-to-remember definitions for each of these five new terms (transparent, translucent, opaque, reflection, refraction). (See the Introduction/Motivation section.)
  2. Divide the class into groups of two students each.
  3. Hand out the worksheets. Encourage and help students, as needed, as they examine the objects listed on the worksheet.
  4. Assist students in choosing two additional objects to investigate.
  5. Once students have completed the worksheets, gather the class back together. Grouping the transparent, translucent and opaque objects together, ask students to help you arrange the objects in a line from transparent to opaque according to how easy it is to see through the object. Discuss the differences in transparencies of the various objects.
  6. Give students time to share what they discovered through this activity, as well as which objects they chose to investigate for their last two objects.
  7. Review the five vocabulary words again and review why engineers care about light. (Answer: Light helps us see, engineers design and build new lighting devices and design lighting systems for public and private spaces.)



Pre-Activity Assessment

Question Why: Ask students, "What does light have to do with engineering?" Be sure to give them a minute to think about it before calling on individuals to answer. Discuss the various ways that engineers are involved with lighting, including creating new light fixtures and light bulbs for all sorts of purposes, designing more energy-efficient lighting and designing lighting plans for public and private spaces. Let students know that the type of engineer that does this is called a lighting engineer.

Activity Embedded Assessment

Observation and Interaction: Assess student comprehension by observing students' investigations and assisting, as needed. Students may especially need help in distinguishing between reflection and refraction, as these sound very much alike.

Post-Activity Assessment

Vocabulary Review: Erase the vocabulary definitions from the board and give students time to think about the definitions. Invite students to share their answers by raising their hands, and writing the definitions on the board.

Activity Extensions

To further experiment with light and shadow, have students make shadow puppets using their hands or objects and a light source behind a sheet.

Place different colored objects in a sunny window, and let students compare degrees of warmth. Ask students why they think the darker objects feel warmer. Discuss the fact that darker objects absorb more light energy, which is why they feel warmer.

Use a mirror to experiment with reflection. Have two students stand at equal angles from a mirror and observe that they can see each other, even though neither one is standing directly in front of the mirror. (This is because images are reflected back from a mirror at the same angle that they enter the mirror).

Discuss with students how black ink (absence of light) on rough white paper (scattered, non-reflective light) makes it possible for us to read.

Activity Scaling

For upper grades, have students give a short presentation on what they discovered in this activity.


Luke Simmons; Frank Burkholder; Abigail Watrous; Janet Yowell


© 2007 by Regents of the University of Colorado.

Supporting Program

Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder


The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education, and National Science Foundation GK-12 grant no 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: August 10, 2017