Consider the Westminister Chimes. If you consider the 4 notes as your elements and the operation of switch (where you swap any two notes), the westminister chimes have all the characteristics of a group. One note of caution....there appear to be a number of 'modified' westminister chimes that alter one note here or there....you have to find the original one). This is particularly effective with math students who are from the fine arts area. They see that math is really infused in everything that is done.