Superintendent Arlene Ackerman doesn't want teachers to sign the individual professional contracts mailed to their homes recently.

She does, however, want them to sign the new one that are coming soon.

"We need to be able to predict the number of teachers who are going to return every year," Ackerman said in an interview this afternoon. "We need to hold teachers and professional staff accountable for staying when they say they're going to stay for the year."

The city's 10,700 public school teachers - and their union officials - are in an uproar over the contracts, sent to teachers' homes beginning last week. Teachers were asked to sign and return the documents, which take effect Sept. 1. The salary field on every contract was left blank.

"It obviously was an error," Ackerman said of the blank salary. "I'm still trying to understand what happened. I was surprised and dismayed."

Teachers haven't signed professional contracts for at least 20 years, Ackerman said, but are required to do so under Pennsylvania school code. It's common practice around the country, she said, and doesn't replace or supercede the collective bargaining agreement the district has with the Philadelphia Federation of Teachers.

The teachers' contracts - and contracts with four other district bargaining units - expire Sept. 1.

Ackerman said principals will be receiving the contracts, too.

Contact staff writer Kristen Graham at 215-854-5146 or kgraham@phillynews.com.