Mystery boxes challenge students to figure out a way to reproduce it's operation and build their own version of it. This particular challenge has more than one solution. Since this is still a project used in my classroom, it's method of operation is not revealed in this video. However, I will share information and plans with anyone interested in making one for themselves. Simply request it in the comments section and give an email address to send the information to. I can remove your email address from the comment section if you do not want it posted.