This was a great video teaching the basic primary and secondary colors: http://www.ehow.com/video_2381649_primary-secondary-color-lesson-kids.html
Also, this video teaches how to draw a quick color wheel. Fun for kids like mine who love drawing, coloring, and painting. :o) http://www.youtube.com/watch?v=quEI2wDaPPE
I'm also using a few of the suggested activities and websites from Lesson Pathways, which I just found out today is now totally free!
I'll try to get some pics posted of our sundial when we get it started. :o)