REVERE – School Superintendent Paul Dakin doubts he can obtain state money needed to hire 15 additional teachers to reduce class sizes in the city’s elementary schools.”The class sizes are too high, especially in the lower grades. It’s not good,” Dakin said, repeating his warning that class sizes and other concerns will become major problems next year if the city cannot secure $6.8 million to $7 million in additional state money.”We’ll be in a very difficult situation next year if the state does not come through with the money to expand,” Dakin said Wednesday, a day after local public school students went back to school.Dakin said kindergarten classes in one school are starting the year with 29 children and fourth and fifth grades throughout the school system have an average of 26 students per class with 25 in other grades.Tuesday was opening day for the new Rumney Marsh Academy and September and October will see school officials seeking out bids for contractors interested in building a new Paul Revere School.Five hundred middle school students from across the city attend Rumney and 400 Paul Revere School students started their year in a wing of the Beachmont School.Dakin said anticipated traffic backups and confusion on roads around Rumney and on American Legion Highway did not materialize. He also said a change in school starting times at the Whelan and Anthony schools so far has not caused traffic problems on par with the ones West Revere parents faced when the two schools opened in 2006.”In some ways the traffic was evened out by people who have kids in both schools and new arrivals,” Dakin said.Over 100 new students from other cities enrolled in the school system this year reflecting what Dakin called “unbelievable movement between Revere, Chelsea and Boston” by parents who live in one of the three cities for a period of time before moving to another.The School Department responded to the high rate of student mobility this year by opening a centralized parent information and registration center at Beachmont.Whelan, as well as the Garfield Middle School, introduced an extended school day this year beginning at 8 a.m. and finishing at 3:45 p.m.Dakin would like to get state approval and funding to expand extended day to Beachmont, Paul Revere, Garfield Elementary, Anthony Middle School and the McKinley School.