Here's how far behind the Hillsborough County School District and its teachers union are in this year's salary negotiations:Tired of contract negotiations dragging on until after Christmas, the two sides agreed last year to begin bargaining no later than May 1 for the upcoming year.By that logic, 2018-19 bargaining is two weeks away.And they haven't agreed on a contract for 2017-18.An impasse hearing, before Special Magistrate Mark Lurie, is scheduled Monday at 9 a.m. in the School Board Auditorium, 901 E. Kennedy Blvd. It is expected to last all day.The hearing continues Wednesday, April 25, 9 a.m. at the Hillsborough Classroom Teachers Association offices, 3102 N. Habana Ave."The magistrate will listen to both sides and make recommendations," said Stephanie Baxter-Jenkins, executive director of the teachers' union.The union declared an impasse shortly after the district – after months of uncertainty – said it could not honor a pay plan negotiated in 2013, during teacher reforms in partnership with the Bill and Melinda Gates Foundation.That plan would have given roughly a third of the teachers a $4,000 raise.District leaders said that would cost them $17 million, and they could not afford such a recurring expense at a time when they are trying to balance spending. The union disputed the $17 million figure. The district offered a one-time bonus package of $1.8 million. The union, calculating that it amounted to $92 per employee, called the offer an insult.Since then, there have been loud protests outside the School Board meetings and passionate testimony from teachers who feel undervalued, who are struggling to meet their expenses, and who are seeing coworkers transfer to higher-paying jobs at other districts.Six weeks remain before this school year ends.