From The Chicago Tribune: The traditional 180-day school year is more myth than reality in Illinois. A jumble of state laws, rules and waivers enable districts to chip away instruction time, shorten school hours and cut the number of days students come to school. Illinois requires 176 days of "actual pupil attendance" — already fewer than most states — but the vast majority of public school districts dip below that by one or two days and sometimes more, a Tribune analysis shows. Some 400,000 students in Chicago Public Schools attend school 170 days, with permission from state lawmakers. A similar waiver allows a suburban district to shave eight days off its calendar so teachers can work on improving student achievement when students aren't there.