Have Primary Colors Changed?

When I was in elementary school, I learned about the color wheel:

I recall choosing purple and yellow to make an opposite picture in art class.  In fact, my oldest, Zoe, even learned about the color wheel in Kindergarten last year.  I realize she had an art teacher as her Kindergarten teacher, but she knows vividly what colors make other colors (i.e. red and blue make purple).

Then we took our second trip to the Wizard of Oz exhibit at the Henry Ford Museum in town.  Since we were one of the few families there on the second visit, we were able to read and participate in more of the activities available.

Here is one that frustrated Zoe to no avail, and I must add that I befuddled that such an activity existed.

So Zoe reads, "Red, Green and Blue are the primary colors.." and she says, "Mommy!  Green is NOT a primary color!"

I realize that "light" is created by red, green and blue.  However, a more appropriate way to state the above would be the following from Wikipedia:

The impression of white light can also be created by mixing appropriate intensities of the primary colors of light: red, green and blue (RGB), a process called additive mixing, as seen in many display technologies.

My issue was not at the fact that you can make light using the three colors, but they are not THE primary colors that make light; rather they are the three colors that when mixed create white light.

However, the display did not end with the above picture.

Zoe looks and says, "Mommy, Green and Red do NOT make YELLOW!"  And in all honesty, this lovely color wheel is very difficult to explain to a child who does not like to see things differently then what she has learned.  The above picture might be the "MAGIC" mixing guide, but lets be real - green and red do not make yellow on a color wheel.  

What is truly interesting, is that the original Horse of a Different Color was every color of the rainbow (red, orange, yellow, green, blue and purple).  However, by doing the hands-on activity Zoe was not able to make the horse every color of the rainbow.  And white light had nothing to do with the Wizard of Oz.  

My mother, a retired school teacher, stepped in and tried to make the horse each color shown above using the knobs in the center console, and was unsuccessful.  She also suggested that with the preschool activities elsewhere in the exhibit (the average age level would be 3-5), this middle school physics concept of light was really out of place.

Just to give you a brief idea of the exhibit, I have embedded a video below from its appearance last year in Minnesota: