Today is the last day of the 2008-209 Knoxville school year, and retiring teachers in the district are calling it their last.  Mark Mahoney, a middle school art teacher, is retiring after 27 years of teaching, high school shop teacher Stan Petersen is also retiring after 27 years, and east elementary councilor Sue Siedschlag is retiring after 12 years, among other staff.  Superintendent Dr. Randy Flack says faculty and staff hold an event every year to honor all the years of service retiring employees have given to the district.