Did you know the Elkhart Area Career Center operates a preschool for 3 and 4 year olds from September through May? The preschool is run by licensed child-care providers with assistance by teenage students enrolled in the Career Center;s Early Childhood Education classes.    The program is located on the east end of the Career Center. Developmentally appropriate activities and experiences are planned daily.   Classes for 3 year olds are held Monday, Wednesday, and Friday from 8:20 to 10:35 a.m. The monthly tuition fee is $48. Classes for 4 year olds are held every weekday from 12:30 to 2:35 p.m. Tuition is $80 a month.   Registration forms are available at the main office of the Career Center from 7 a.m. to 3:30 p.m.  There is a $40 registration fee.    For more information, call the Career Center at 262-5650.