I think it is your version of a teacher planning day but you can call your DISTRICT office and ask them. You have a Parent Relations phone number - ###-###-####.
Under state law, there must be 180 days of school. Early release days count as long as they have lunch there (again, part of the legislation regarding early release). Typically, early release is used for teacher and district meetings while teacher planning is closing out a marking period. Your non-student days seem to coordinate with the end of the marking period except for the 3rd quarter. In the old days, teachers would keep grades in a grade book, average them, and then complete bubble sheets which they would turn in at the end of the quarter. Now, they keep grades on a computer, average on the computer, but they have to actually upload all of those grades WHILE at school. It is not something they can do from home. Believe it or not, here in Broward County, on the days that grades need to be uploaded, the computer system will often be oversubscribed so that it can take hours to upload. I've watched my mom and stayed late with her at her school. Technology really didn't help the teachers with grading too much.
Yes, Broward County JUST revised our school calendar about 2 weeks ago to furlough everyone for the Monday and Tuesday of Thanksgiving week. We already had Wednesday, Thursday and Friday off. Now everyone is scrambling for daycare.
It is tough on working parents, but really, I think the teachers are truly getting the shaft - they will not get paid for those furlough days.