Every year on the 150th day of school, I hang up our "Countdown to First Grade" gumball machine! Each day my calendar helper moves the gumballs to show how many days are left of kindergarten. It's a great way to reinforce subtraction and number recognition! The gumball machine was drawn on poster board, colored and then laminated. I used Velcro on the machine and individual gumballs. I normally use clips to hang the display from one of my pocket charts beside our Promethean Board. I have a number line on the wall below our PBoard to help students subtract.