By Mike DeNardo

PHILADELPHIA (CBS) — It’s back to work today for Philadelphia’s public school principals.

The principals were beginning their year with a training session today at Fels High School.

Last March, the principals’ union agreed to contract concessions that made them ten-month instead of year-round employees.  But principals’ union president Rob McGrogan says his members have been working straight through the summer, hiring staff and meeting with school teams.

“While we are working officially a ten-month year, you’re doing that work over a 12-month period,” he noted today.

More than 40 of the city’s 214 schools will have different principals this fall.  McGrogan says the fiscal crisis has bred more uncertainty for his members.

“Most of the research shows that administrative stability is an indicator to a school’s success.  We see that we’re starting fresh in far too many institutions,” he said today.