Very effective picture; clear and crisp. Couple of suggestions for whatever they are worth: would have liked to see the colors lined up diagnolly instead of as they randomly appear. Smudges are distracting. The brown (blue dust on green) was also distracting. I think it is because the picture is so clear that these imperfections become magnified. As I said, nice shot!
Too bad about the green mark on the white chalk. Great array of colors - what would this look like if you mixed them up a bit more, or if the blue were in the place of the orange? :)
Nice photograph, not really bright colours, but interesting ones; good focus, good lighting, nice idea for the challenge, shows good imagination on your part.