Petaluma City Schools students know when they will start the school year, they just don't know for certain when they will finish. With the exception of two schools, Penngrove and Mary Collins Charter School at Cherry Valley, both on a year-round schedule, Petaluma City Schools open Wednesday, Aug. 21. Penngrove and Cherry Valley students have already returned to their classrooms.

The plan is for a 180-day school year, ending June 6. However, the 180-day plan has not been approved by he Petaluma Federation of Teachers. The teacher's union and school district are currently at odds over proposed changes to he current contract.

"Our expectation is to have 180 school days, but we don't have an agreement (with the PTF)," said Petaluma Schools Superintendent Steve Bolman.

The Petaluma City Schools District is also planning to expand kindergarten days by 88 minutes four days a week, a proposal that has also not been agreed to by the teachers.

The school district and PTF agreed to declare an impasse in their negotiations last month and asked that a state mediator be brought in to assist in negotiations. Bolman said last week that the district has not heard back from the state, and no mediator has yet been appointed.

Despite the lack of agreement over the contract modifications, the school district is moving forward with several changes in the upcoming school year, including implementation of a new $2 million technology plan designed to make every student and teacher technology proficient and equipped with the tools to use their knowledge by 2018.

For the first time, both Petaluma and Casa Grande high schools will have full-time, paid athletic trainers at practices and games for all major sports. The trainers will also perform baseline testing of all athletes to help monitor for possible concussions.

A major facelift has been completed at Casa Grande High School, where an ongoing effort to re-side all of the campus buildings finished with work on the E building, the largest building on campus, and the adjacent H building, which houses the counseling offices. At Petaluma High School, the 50-year-old gym floor has been replaced.

Petaluma City Schools has also begun focusing on the new common core standards teaching methods, which stress critical thinking, communication and collaboration. "We want students to understand what is behind what they are doing," said Jane Escobedo, assistant superintendent of educational services for the district. California's standardized testing will be based on common core standards beginning in the 2014-2015 school year.

Many students entering Petaluma schools will have new principals when the doors open Wednesday.

Sheila Garvey steps in at McNear Elementary school. Chad Carvey is the new principal at Mary Collins Charter School at Cherry Valley. Renee Semik replaces long-time Petaluma Junior High School principal John Lehmann as head of both the junior high school and the Sixth Grade Academy located on campus.

There has also been a shift in the district's alternative schools, with Rusty Sims becoming principal of Valley Oaks elementary and high school as well as San Antonio High School. District newcomer Greg Stevenson replaces Sims as principal of both Carpe Diem and Sonoma Mountain high schools.

Teacher Becky Lofton will not only continue her teaching position, but also serve as principal at Crossroads Junior High.