Castle High School is changing its grading policy and moving to small "learning communities" centered around potential career paths as part of an effort to boost achievement and help more students get to graduation day.

The changes, to be discussed tonight at a meeting for parents and community members, are part of a bigger redesign of the school.

Castle has for years struggled to improve student performance. Its graduation rate last school year was 72 percent, 8 percentage points lower than the state average. Thirty percent of Castle 10th-graders tested proficient in math last year, and 61 percent were proficient in reading.

Castle Principal Meredith Maeda said the changes are aimed at emphasizing learning and meeting tough standards, rather than striving toward a particular letter grade. The changes include:

» A new standards-based grading policy, which does away with percentages and uses numbers assigned to a letter (a 5 is an "A," a 1 is an "F" and a zero is given only if no work is done).

Teachers would assign a grade by figuring out how many concepts students met in an assignment, rather than simply by counting how many answers they got right.

» Homework or in-class "formative assessments" will be graded but will not count for or against a student. Only "summative assessments," such as midterm and final exams or large reports, will count. Also, students who fail summative assessments may retake them if they have shown understanding of the work in previous formative assessments.

» Small learning communities will be in place starting with the new school year. Freshmen will have one community. Sophomores will opt for one of three, either arts and media, medical and electronic technology or business, culinary or natural resource studies. Students will remain in their communities through graduation.

Maeda said putting students in such groups tailored to their interests and rethinking how they are graded shifts the focus from grades to learning.

"How do you support your child in the realm of learning, not just doing stuff to get paid (by a grade)?" Maeda said. "We’re changing the attitude. Our focus is on student learning and joint responsibilities."

He said about 60 percent of teachers already have moved to standards-based grading, and the rest will convert by the end of the school year. With the change, he said, grades at the school have improved.