No. It's not nine months of work. I counted the actual days the teachers are in class on the official school calendar. They work an average of 6 months.
Remember the holidays, winter breaks, spring breaks, etc. When the kids are not in school, neither are the teachers.
The legal minimum for an Illinois public school year is 176 days of “pupil attendance.” If a school doesn’t meet that minimum, they lose 1/176th (.56818%) of their state funding for each day they fall short.
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Wisconsin Public School Observance Days
2010-11 School Year Observance Days
September 16 Mildred Fish Harnack Day
September 17 U.S. Constitution Day
September 17 POW-MIA Recognition Day (Third Friday in September)
September 22 Wisconsin Day (Wednesday of the third full week in September)
September 28 Frances Willard Day
October 9 Leif Ericson Day
October 12 Christopher Columbus Day
November 11 Veterans Day
January 15 Martin Luther King Jr. Day
February 12 Abraham Lincoln’s Birthday
February 15 Susan B. Anthony’s Birthday
February 22 George Washington’s Birthday
March 4 Casimir Pulaski Day
March 17 “The Great Hunger” in Ireland
April 9 Prisoners of War Remembrance Day
April 13 American’s Creed Day
April 19 Patriots’ Day
April 22 Environmental Awareness Day
April 29 Arbor Day (Last Friday in April)
June 14 Robert La Follette Sr. Day
(Public) schools must be in session for 175 days, and must include “x” number of hours. Most public school districts schedule 181+ days
Wisconsin also requires 875 hours of instruction per academic year which usually takes place over the course of 175 days