I am an elementary/middle school science teacher and bring in a machine for about 9 to 12 weeks. I introduce them to it during Simple Machines, laws of motion and forces etc. And they take a pen/Paper test and then a second test where they play pinball and have to identify between balls where they saw the topics we have discussed. After that it remains in the classroom for them to play as an incentive, reward, brain break or after school activity. (I have found the number of visits to my room by fellow teachers in the morning greatly increases when a machine is in there)