Science : Mixing Water

We did a WATER experiments. I prepared 3 small bowls with water inside. Then, I gave Fritz 3 primary colors - yellow, blue and red food coloring. I asked him to drop a bit on to the water. Using a pipette, Fritz mixed these 3 colors into green, orange and purple to the ice cube tray. After that, we put the tray into the freezer. Few hours after, he played with these cubes during his bath time. He's extremely excited though all the cube mixed together into a dirty color, like a mud. :P