Let them run until the colors are separated sufficiently to tell whether the green is a true green or a mixture of blue and yellow. Imagine you're in a blimp over the Olympic track stadium, and below the 100 meter dash is just about to begin. But instead of only one person per lane, imagine 100 people in a lane. The race is a sprint, and you take a snapshot when the first runners cross the finish line. Dyes run slowly.
Dyes run akimbo.
The two wires should be parallel to each other. For Further Sleuthing Let the students make their own mixtures of the concentrated dyes . Use small test tubes or any clean vial. Note that the student can vary the colors, and the relative amount of each color, in the mixture.