The mystery color is only reveled when you flip the marker to switch the color.
AGE: 3 and up
This is why Yellow Springs Toy Company loves this brand:
This company provides support to teachers and students with fun and creative supplies allowing them to add happy to classrooms across the U.S. Together with AdoptAClassroom.org , they have funded over 105 classrooms, supported over 2,500 students, and donated over $150,000.