Today's impasse announcement should come as no surprise to close watchers of the negotiations.

For months, the district and the union have

. Here are some of the biggest differences:

PPS contract talks: The sticking points Issue District view Union view Teacher workload : The Portland teachers union has long had a clause that most districts don’t have: the district can’t force teachers to exceed a workload last calculated in the 1997-98 school year. Eliminate workload clause but create a separate agreement preserving current workloads for two years. The district says the provision has limited its ability to save money and add instructional hours in high schools by assigning teachers more than 180 students per term. Keep it. Teachers are already exhausted and overwhelmed, union negotiators say, and it that would only get worse without the limit on how many students a teacher can supervise. Pay raises 2 percent in 2013

1.5 percent in 2014

1.5 percent in 2015 4.8 percent for 2013-14

3.75 percent for 2014-15 Health insurance Cap district’s monthly contribution at $1,431 per teacher, then increases 2 percent in years 2 and 3, raising the contribution to $1,489 per month. District continues contributing 93 percent of each teacher’s insurance premiums.

All of the issues are far from new.

Past board members have decried the union's health insurance costs and the workload provision became a hotbed of controversy when the district tried to unilaterally implement a new high school schedule.

The two sides seem particularly deadlocked on health insurance and the workload provision, which both sides have identified as priorities.

Superintendent Carole Smith this morning said that class sizes -- or the workload provision -- does not belong in a contract, while the teachers union president in the afternoon said teachers have identified class sizes as one of their biggest issues.

-- Nicole Dungca

Follow @ndungca