On Sunday, the final day of the World Science Festival, Alan Alda hosted an event to announce the winners of his third annual Flame Challenge, in which he tasks world-class scientists with explaining an abstract concept in a way that makes sense to 11-year-olds. The kids pick the topic (well, a young Alda was responsible for the first year's question: What is a flame?) and judge the submissions. This year, thousands of students in schools around the world voted on written and video entries explaining "What is Color?"

Before announcing the winners, Alda brought out three scientists to explain to the largely elementary school aged audience different facets of the concept of color. Jay Neitz from the University of Washington explained the basic mechanism of how the three different kinds of cone cells in the retina process different wavelengths of light as different colors. The cones register light as red, green, or blue, the different combinations of which render all the thousands of colors we see in the world. While most other mammals, like dogs and cats, have only two kinds of these cones, mantis shrimp have 12 different photoreceptor types—the most in the animal kingdom—and can see a whole range of colors we can't even imagine.

Next up, artist and scientist Bevil Conway demonstrated the mind-boggling power of color induction—or, how a color can look completely different based on the surrounding colors—with a Josef Albers-style painting exercise (see some examples of similar illusions here). He showed a series of slides illustrating how artists use, or subvert, this quirk of neuroscience in their work.

David Eagleman of Baylor College of Medicine explained the offshoot of perception that is synesthesia, or the blending of senses, particularly as it includes color association. After a scientific introduction—as much as 3 percent of the population is synesthetic—he introduced neuroscientist, violinist, and synesthete Kaitlyn Hova who, with the help of some lighting tricks, demonstrated what sound-to-color association can look like.

The event concluded with the announcement of the Flame Challenge winners. Melanie Golob took home the trophy for the written entry:

And Dianna Cowern's video took first place in the visual category:

You can watch the full presentation online here.