X is for Xylophone.  A rather common item in most preschools is the xylophone.  Tuned to the Orf tones, any child of any age can make lovely melodies on the xylophone.  

Using rectangles of varying sizes, the xylophone can be constructed.  A small circle makes the head of the mallet, and the children can use a marker to make the handle of the mallet.  

Another crazy-fun and most-favored game is played with an X.  With the children, I construct a map of the classroom.  Children take turns hiding something in the classroom and marking it’s location with an X on the map.  The others, in turn, find the object using the map as guidance.