LESSON 1 - The Primary Colors of Light

Students will:

  • Use the primary colors of light to create new colors.
  • Demonstrate their new knowledge of the primary colors of light by coloring a diagram.

Materials Needed:

Worksheet 1 - Mixing Colors of Light (1 per group)

Copies of blank venn diagram


Small flashlights (3 per group)

Red, blue, and green theatrical gels or cellophane


White paper


IMAGERS color mixing page at http://science.hq.nasa.gov/imagers/color


Show students the three flashlights. Ask them if they can identify anything unique about this combination of colors. Explain that today’s activity will give them the opportunity to experiment with colored lights.


Divide students into groups of four. Provide each group with three flashlights, a red, green, and blue color theatrical gel, and three pieces of tape. Each group should also have a copy of worksheet 1. Have students tape the gels around the face of the flashlight so that no white light leaks out. Assign one to each student in the group. One will be the recorder and three will hold a flashlight. Tell students to use their flashlights to mix the colors of light. As they make discoveries, ask the recorder to describe the color they created. Have the group quantify the amount, or intensity, of colored light used. (See directions and example on worksheet 1.) After a few minutes, have the students exchange roles and continue mixing colors. (see answer key)


After students complete the chart, as a class discussion, ask them to describe the colors they created. Make a list on the board. (Optional: Use stage lights to demonstrate the colors they name.) Review the following combinations and give students the "proper names" for them.

Red + Green = Yellow

Red + Blue = Magenta (pinkish purple color)

Blue + Green = Cyan (turquoise)

Red + Blue + Green = White

The absence of light = Black

Then, ask students why red, green, and blue are so unique. Lead them to understand that these three colors are the primary colors of light. Explain that red, green, and blue mix to make all colors.

Distinguish the primary colors of LIGHT and the primary colors of PIGMENT from each other. Red, green, and yellow are the primary colors of PIGMENT, or paint and crayon. They cannot combine to make the products of the primary colors of LIGHT. (See venn diagrams.)


Relate this new information to computer monitors. Explain to students that computer monitors combine red, blue, and green to make the colors that we see. Our monitor can display hundreds and thousands of colors. Give students a copy of the blank venn diagram. Have them label and color in the diagram using the information they learned in this lesson.


Ask students to name the primary and secondary colors of light. Use the completed venn diagram to assess their understanding of the primary color combinations.

Tips for Teachers

  • Flashlights - Have each student bring in a flashlight for this activity. Or, ask a local company to donate mini-flashlights.
  • Color filters - Purchase a large sheet and cut it into small squares. Or, find a theatrical store and ask for a filter swatch book. Make sure to select a red, blue, and green filter combination that best represents white when combined. Because filters are traditionally used on high-powered stage lights, the exact same color filters used for stage lighting may not produce the desired effects with low-powered flashlights.
  • Unlike adding more paint or crayon to get a darker color, adding more colored light does not give a darker color. Higher numbers (amounts of) will create a lighter color (i.e. all 9's equals white). Lower numbers will create a dark color (i.e. 1,0,0 would be a dark red)



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NASA Official: Ruth Netting
Last Updated: March 27, 2007
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