I started teaching my oldest two kids their colors several months before their second birthdays. I began by taking alphabet magnets in two different colors and having them sort them into two containers. It took a few easy lessons and they had the concept down pat.
A few months ago, I began this project with Owen. You know what happened? He had no clue what a color was, but he learned all the letters of the alphabet!! For awhile, I stopped working with him on colors and we fully immersed ourselves in letters and sounds. Just recently I decided to try colors again with a new manipulative.
This time I used colored math chips. I chose two colors and had him sort them into two bowls. He immediately understood the concept and by the next day, he was sorting four colors at a time. He is still very shaky on the names of the colors, but the first steps (understanding the concept of color and learning to sort) have been mastered!
(Another fun way to work on colors is using colored M & Ms! Fun for Mom, too!)