PORTLAND, Ore. — Oregon students performed slightly better on state tests than they did a year ago, scores released Thursday show.

The exams taken by nearly 300,000 students this spring are designed to reflect how well schools helped students meet rigorous Common Core standards in English and math.

Fifty-five percent of students met the standards in English — up 1 percentage point from 2015. Forty-two percent of students were up to standards in math, also an increase of 1 percentage point.

Though the improvement was minor, Oregon schools chief Salam Noor noted that it was enjoyed by all types of students, including minorities, students with disabilities and those living in poverty.

“What is most exciting about this year’s results is the progress made by students across the board, including those from groups that have historically performed at lower levels than their peers,” Noor said.

The tests are taken by students in third through eighth grades and 11th grade. Compared with results from 2015, more third-graders mastered mathematics and more fifth-graders mastered English.

High school juniors improved in English and math. But those 11th-grade results aren’t as reliable because many juniors declined to take the exams. Many see the exams as an unwelcome duplication of SAT, ACT, Advanced Placement tests or similar tests that also measure college readiness, said Heather Beck, the superintendent of the Lake Oswego School District and a strong proponent of Common Core standards.

Reacting to concerns that schools overemphasize testing, legislators passed a law that took effect Jan. 1 that allows parents to opt their children out of taking the tests for any reason. Previously, students could only be excused for religious or medical reasons.

As a result, Portland, Eugene and several other districts had participation rates below 90 percent.

Bend’s three high schools recorded some of the lowest participation rates in the state.

“There’s absolutely nothing we can do with the high school data. We can’t draw any reasonable conclusions because the participation rate was below 50 percent,” Dave Van Loo, the district’s director of school improvement, told The Bulletin newspaper.

Among high schools, Lakeridge in Lake Oswego had the top in performance this year, with 68 percent of juniors demonstrating full proficiency in math and more than 95 percent in reading and writing.

“We use the standards as a pathway to help kids become career and college ready,” Beck told The Oregonian/OregonLive, “and the assessments tell us if we’re on the right pathway.”