AUBURN — As school populations decline statewide, Auburn’s enrollment is expected to continue its recent growth trend.

That’s healthy for the school department, since money it receives from the state for education is determined to a large degree by the number of students.

But the numbers are starting to cramp school buildings.

“We’ve maximized every space we can in schools,” Superintendent Tom Morrill told the Auburn School Committee on Wednesday night. “The inn is full.”

What’s driving the increase is more elementary school students. Park Avenue, which is less than five years old, was built for a capacity of 325 students. Next year, it will house 370, Morrill said. He added that the state did not allow Auburn to build a bigger school.

Elementary school principals are monitoring new enrollments and working with each other, sending or receiving students, to ensure no classes are too large. In several cases, multiage classrooms have been created to prevent overcrowding, Morrill said.

Auburn’s largest class, with 27 students, is the fourth grade at East Auburn School. Two other fourth grades at Sherwood Heights each have 26 students. Overall, Auburn has six kindergarten classes with 19 students each and 10 kindergartens with 17 or fewer students. System-wide, first grade has a low of 17 students per class and a high of 22.

Grades K-3 class sizes range from 15 to 22; and 21 to 23 for grades four to six.

At the Auburn Middle School, class sizes average 24 students. At Edward Little High School, classes have between 14 and 16 students, on average, Morrill said.

Auburn has reversed a trend of declining enrollment, Morrill said. Looking at recent years, the lowest student population was 3,467 in 2005-06. This year, the student population is 3,612. Next year’s numbers were not yet in but are expected to be slightly larger, Morrill said.

In other business, accountant Hank Farrah of Runyon, Kersteen and Ouellette gave the school department high marks for having a “clean” audit with no issues for 2009-10.

Committee members approved a request from Morrill to apply for a $70,000 grant from state and federal tobacco money to create a coordinated school health program. If Auburn receives the grant, the program would allow for more anti-tobacco work, better nutrition and more exercise for students, Morrill said.