The Colored Shadows Interactive is an adjustable-size file that displays nicely on smart phones, on tablets such as the iPad, on Chromebooks, and on laptops and desktops. The size of the Interactive can be scaled to fit the device that it is displayed on. The compatibility with smart phones, iPads, other tablets, and Chromebooks make it a perfect tool for use in a 1:1 classroom. 

Teaching Ideas and Suggestions:

This Interactive is one of several Interactives in this section that pertain to the topic of color addition, color subtraction, filters, and color vision. In this Interactive, learners explore how colored lights become blocked and result in tihe formation of a "color shadow" on the screen located behind the person. Three different lights can be turned on and off, resulting in various colored shadows on the screen behind the person.The phenomenon provides a great application of both color subtraction (the person blocks or takes away some of the incident light) and color addition (the incident light that reaches the screen combines together to produce a different color). Furthermore, the interaction of the incident light with the person's clothes reveals the color of the clothes under different lighting conditions.

If you are able, we recommend preceding the use of this Interactive with a demonstration of the same phenomenon. The demonstration will require that you have three colored spotlights available to project upon you and a screen behind you upon which the colored shadows can be cast. Begin with one light at a time and get students to understand the "geometry of shadow formation." A light placed to the left side of you will cast a shadow on the screen on the right side of you. One your understand the geometry of shadow formation, begin experimenting with various combinations of two colored lights. Once you've done the demonstration, allow students to explore the physics of shadow formation with this Interactive. We do not have an exercise sheet to accompany this Interactive. However, we do have a exercise on the topic of shadow formation in the Curriculum Corner (see below). And mission LC9 of Minds On Physics is the perfect complement to this Interactive.

The concept of colored shadows is difficult for students. We receommend saving this Interactive until the end of the learning cycle on color subtration.


Related Resources

There are numerous resources at The Physics Classroom website that serve as very complementary supports for the Colored Shadows Interactive. These include:
  • Minds On Physics Internet Modules:
    The Minds On Physics Internet Modules include a collection of interactive questioning modules that help learners assess their understanding of physics concepts and solidify those understandings by answering questions that require higher-order thinking. Assignment LC9 of the Light and Color module provides a great complement to this Interactive. It is best used in the middle to later stages of the learning cycle. It would be a great follow-up to the use of this Interactive. Visit the Minds On Physics Internet Modules.

  • Curriculum/Practice: Several Concept Development worksheets at the Curriculum Corner will be very useful in assisting students in cultivating their understanding of color vision, most notably ...

    Reflection, Transmision, and Color
    Color Addition and Subtraction
    Viewed in Another Light
    Pigments and Paints

    Visit the Curriculum Corner.

  • Labwork: 
    Simulations should always support (never supplant) hands-on learning. The Laboratory section of The Physics Classroom website includes several hands-on ideas that complement this Interactive. Four notable lab ideas include ...

    Color Addition Lab
    Taking Away from RGB Lab
    Painting with CMY Lab
    Filtering Away Lab

    Visit The Laboratory.

Additional resources and ideas for incorporating the Colored Shadows Interactive into an instructional unit on Light and Color can be found at the Teacher Toolkits section of The Physics Classroom website.  Visit Teacher Toolkits.


The Physics Classroom would like to extend a special thanks to Nerd Island Studios for the creation of this HTML5 Interactive and for contributing it to our collection of Physics Interactives. Visit to see more great stuff by Nerd Island Studios.

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