maybe what the person says changes during the task from saying the color they are moving from to the color they are moving to and you can say a word at various points during the task that would indicate it is time for the rule to change. take a look at this list and see if any of them can help you. they are designed for a lifetime longer than that of the car itself. this will allow the athlete to have visual feedback which should help their learning and development. they are literally as small as possible get them. 