Reprinted from Connect
Vol.18 No.5, May/June, 2005
Focus on: Light and Color
Grade Level: 3-5
Grade Level: 6-8

Mousing About With Color

Technology for Learning

by Bob Coulter

Hands-on investigations in this issue provide a base from which students can deepen their understanding of how we perceive light and color. Simple, easy to implement technological extensions to the hands-on investigations introduced here can make significant contributions to your students’ view of the world. Color mixing using various combinations of the red, green, and blue colors commonly used for computer displays provide an electronic palette on which your students can mix and match to their hearts’ content.

For teachers who have watched students obsess over just the right color for their text instead of actually writing, this exploration will provide an opportunity to channel their interest. Students can pursue what is, for many, a natural bent to explore. In this case their exploration is within the structure of a curriculum.

Innovative new uses of web technology provide another means through which your students can explore color and light. Beyond a simple repository of information, which alone can be quite valuable, the increasing interactivity now found in web sites allows a deeper exploration of the basic concepts underlying your curriculum.

“Messing about” with colors

Providing students with an opportunity to engage in free exploration with materials before being guided into structured investigations is a time-honored tradition in progressive educational circles. In a phrase so memorably captured by David Hawkins (who in turn borrowed it from the classic novel The Wind in the Willows), students need a chance to “mess about” with colors to deepen their understanding. A premature rush to formalize students’ learning will inevitably result in shallower knowledge than we would like.

Most students know from their art classes that colors are composed of various combinations of primary colors and they will have explored subtractive color mixture using media such as tempera paint, watercolors, crayons, and colored pencils. To explore additive color mixture, such as the kind used in creating colors on a computer screen, color palettes commonly found in software packages can provide an electronic playground.

The examples here use the color tools commonly found in applications that are native to Apple’s Mac OS X. You may find comparable tools by looking in drawing or paint programs, or the color selector associated with fonts in your word processor. In many cases, programs offer the user an opportunity to create custom colors instead of being bound to a small set of choices. Once you have identified a suitable tool, you will be able to support your students in explorations similar to those described here.

First investigation

As a starting point, simple variations of red, green, and blue can be created in seemingly infinite variations. Mathematically speaking, a typical color palette combining red, green, and blue offers 256³, or 16,777,216 color combinations. You can make an interesting link to the optical capacity of your students’ eyes and brain by asking how well they can differentiate between closely related colors. Optical research suggests that humans can only perceive a portion of the colors that are theoretically possible with the “millions of colors” settings commonly found on computers.

Setting the slider on your computer to show a maximum of red with no green or blue is, obviously, red. Scaling back on the red brings colors closer to maroon and eventually to black, sometimes referred to (in light) as the absence of color. Similarly, scaling back from the maximum setting for green creates a darker, forest green before becoming black when all green is removed. These discoveries could be pursued independently or done through a process of guided inquiry in which you pose questions and ask students for their prediction. (”What do you think would happen to the color if we reduced the red setting on the scale?”).

Expanding on the topic

Going further, students can explore how different combinations work together. For example, placing the sliders at 1/3 of each color’s range produces a basic grey color. Varying the blue from there while keeping the red and green constant produces either a dull blue or olive color, depending on whether the blue is increased or decreased. What happens if red and blue are held constant and the green slider is manipulated? Building off of the initial state of each slider being at 1/3 of the range, what would happen if each of the sliders were at 1/2 of the range, or 3/4? How do these results compare with the color you created at the 1/3 position? How does adjusting the opacity scale or any other control affect your results? You and your students can devise many other questions relating to colors seen on your computer monitor.

Students who are ready for an additional challenge can extend their work beyond the RGB (Red–Green–Blue) color modes used in computer displays to the CMYK (Cyan–Magenta–Yellow–Black) mode typically used in publications. In CMYK colors, each of the first three colors is combined in percentages ranging from 0 to 100%, with black used to adjust the darkness of the color tones. For example, a combination of 50% Cyan and 75% each of magenta and yellow produces a brown, which can be made lighter or darker depending on the intensity of the black scale. This system better accommodates how transparent inks are mixed to create colors on the printed page, as compared with the light emitted from your computer screen. Coming to appreciate that different systems are better than others for some situations is an important part of the technological literacy found in most science standards.

Web investigations

As your students build a depth of understanding of how light and color interact, they will be better equipped to read and interpret a range of materials online that explain the physics behind the phenomena they are investigating. Of course, many sites pursue science concepts at levels well beyond what a typical elementary or middle school student is capable of comprehending. As with any web exploration, you may find it productive to guide students to specific web sites that are appropriate and productive. When looking for sites for students, I often find the Yahooligans site ( http://www.yahooligans.com) to be useful, since the sites they select are screened by educators based on their appropriateness for a student audience.

One site I found there provides a strong complement to the color mode investigations described above. The Color, Vision, and Art pages developed by Web Exhibits ( http://www.webexhibits.org) provides innovative explorations of color, including a site with classic works of art. In the “light, color, and vision” section, positioning the cursor over a place on the art work shows the color composition at that point on the picture. Another portion of the site, “Luminance and Equiluminance,” allows students to manipulate on screen aspects of the colors found in the historic work. While some may consider this a sacrilege, done well it provides the basis for a discussion of the masterful use of color in the original and a strong link between science and art. Together with other explorations of color, you will go a long way toward helping your students to see the science and mathematics of the colors we see every day.

The Mathematics of Color

As you and your students engage in these explorations, be sure to notice the many possibilities for mathematical skill development. The color scales in RGB are typically “8-bit” colors, allowing for 2⁸, or 256 different settings for each of the three main colors. As noted in the text, this provides (2⁸)³ or 16,777,216 possible permutations of colors. In the CMYK color mode, the colors are represented in percentages of intensity. As with the use of exponents in RGB colors, work with CMYK colors provides opportunities to develop critically important mathematics skills. Impromptu “just in time” lessons can be provided as needed to extend your students’ understanding of color as they deepen their appreciation for the power and usefulness of mathematics.

Copyright © 2006 Synergy Learning International, Inc. All rights reserved.

Bob Coulter - Bob Coulter is director of Mapping the Environment, a program at the Missouri Botanical Garden's Litzsinger Road Ecology Center that supports teachers' efforts to enhance their science curriculum through the use of the Internet and geographic information system (GIS) software. Previously, Bob taught elementary grades for 12 years.
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