SALEM — About 88 percent of the class of 2007 finished four years of high school last June, according to new numbers released Monday by the state Department of Education.

SALEM — About 88 percent of the class of 2007 finished four years of high school last June, according to new numbers released Monday by the state Department of Education.

But the numbers don't reflect how long it took them to graduate — some might have finished in the traditional four years, academic whizzes in three or less, and some students might have spent five years or more in an Oregon high school.

And it's about to get harder for Oregon students to graduate on time: Starting with next year's ninth-graders, the number of credits required to graduate will increase, and students will have to show that they've mastered a set of "essential skills."

According to the Education Department's numbers, 38,520 students graduated from Oregon high schools last year, with 33,446 of them earning a regular diploma.

"The new graduation requirements may slow down the increases in the graduation rate we're looking for," said Medford schools Superintendent Phil Long. "It raises the bar as far as the rigors of the requirements for a diploma."

Some schools in Jackson County, such as Ashland and Medford high schools, already require students to complete 24 credits or more to graduate.

District officials are concerned they won't be able to find enough people to fill advanced math teaching positions that will be needed to offer enough sections of math and science to meet diploma standards.

"It's challenging getting teachers who are certified in Algebra 2 and above," Long said. "Going into private industry is much more lucrative."

Members of the class of 2007 will be among the last in the state to receive certificates attesting that they had passed tests in core academic subjects and turned in eight acceptable classroom work samples.

The certificates, known as "CIMs," never caught on widely in Oregon classrooms, and Oregon universities never made them an admission requirement. Finally, the 2007 Legislature phased them out, in favor of the new diploma requirements. After the current school year, schools will no longer be required to offer a CIM.

Among the class of 2007, only 29 percent emerged from high school with a CIM, a slight dip from 2006, when 31 percent of high schoolers graduated with a CIM. The historical high was 37 percent in 2005.

Under the new standards, before they can graduate, Oregon students will have to demonstrate "proficiency" in reading, writing, math, public speaking, technology, thinking, civic engagement, global literacy and career skills.

The state Board of Education still hasn't finalized how they'll measure "proficiency"; options include a portfolio of work, or a standardized test.

Among last year's graduates, 929 of them earned a modified diploma, which is given to special education students, and another 481 got an honorary diploma, usually given to foreign exchange students.

The remainder of the students finished their four years, but still had to earn several credits to get a diploma. Most planned to attend summer school.

At Redmond High School, about 50 percent of the class of 2007 got their CIM, Principal Jon Bullock said.

"For the past few years, much of our coursework has been designed around making sure students could be prepared to earn the CIM," Bullock said. "But now, we are building all of our curriculum planning around new graduation requirements, beginning this year."