To prepare this center, number ten gumball machine cutouts and program each one with a different addition problem. Place the cutouts and a container of colorful pom-poms (gumballs) at a center. The student uses the gumballs to help him/her solve each problem. Another variation of this activity is to give each student one gumball machine sheet. Prior to the lesson, pre-cut gumballs using a variety of colors of construction paper and place in a baggy. Have the students develop their own addition problem and then write in their numbers. I mounted the gumball machines on red construction paper and hung them up in my classroom for administration & parents to see!