Students in southern Michigan and Pennsylvania are enjoying an extended summer vacation as a result of the first teachers' strikes of the new school year.

In Stockbridge, Mich., classes for 1,893 students were to open Tuesday but educators and support workers walked off their jobs Monday, their first day to report. It was Michigan's first walkout of the new school year.Some 4,700 students of the Mechanicsburg Area and Moshannan Valley school districts in Pennsylvania also got a reprieve from returning to classes as teachers walked out, canceling the first day of classes Tuesday.

In Mechanicsburg, Pa., no further talks were scheduled after negotiations broke off Sunday between the school and its 208 teachers, said Carlin Wenger, spokeswoman for the Pennsylvania State Education Association, the state's largest teachers' union.

Job security and dismissal are said to be the stumbling blocks in reaching a tentative agreement between the district and its teachers.

The 79 striking teachers in the Moshannan Valley district are seeking increased salaries and benefits and plan to meet with district officials on Sept. 6, according to district board president Samuel Pollick.

The Pennsylvania Federation of Teachers, which represents about 100 districts, said four remained without a contract and one, Scranton, could lead to a strike by some 700 teachers next week.

Eight districts in the Philadelphia area are currently in negotiations, said Donald Morabito of the PSEA. While seven of those are authorized to call strikes, only West Chester, Penn Ridge, Spring Ford and Cheltenham school districts appear to be headed for strikes, he said.

In Stockbridge, Mich., negotiations with the district's teachers' union, an affiliate of the Michigan Education Association, were not slated to resume until Friday.

The strike at Stockbridge affects three MEA-affiliated unions representing some 250 teachers, food service and office workers as well as teachers' aides and bus drivers.