State refines how it tracks MCAS scores

But using a new measuring tool unveiled yesterday, one that is based on students’ rate of improvement, the O’Donnell is out-shining many affluent schools across the state.

The new method is being called a major milestone in MCAS history and a distinct break with tradition.

For more than a decade, the state has judged a school’s MCAS success by comparing each grade level with the ones before it; this year’s fourth grade results, for instance, would be judged against last year’s fourth grade scores.

That method will remain in place but added to it will be a new analysis that measures whether individual students are making gains on the Massachusetts Comprehensive Assessment System tests they take over the course of several years. Schools, in turn, would be assessed on whether their students are exceeding expectations over time or falling short.

The new system, state education leaders say, should offer educators a wealth of new information about what may or may not be working in classroom instruction, which teachers are having the greatest effect, and which students are not living up to their potential.

Based on data released yesterday, the new system already is casting some schools in a different light, uncovering mid- and low-performing schools that are demonstrating high rates of improvement, as well as high-scoring schools that have not been pushing their students ahead as quickly as they could.

Conversely, in many cases, the new data underscore previous findings, with some high-achieving schools posting some of the fastest gains and some of the lowest-performing schools appearing to fall further behind.

Professional associations representing superintendents, school committees, and teachers yesterday applauded the new approach, which they said injected some much-needed fairness into the state’s school accountability system. They have long complained that simply comparing students with their predecessors at a certain grade level was too much of an “apples to oranges’’ approach. Academic skills of students can vary greatly from one year to another, they said, causing some school leaders to dismiss poor MCAS scores as the result of a less talented batch of students rather than any instructional deficiencies.

“I think the [new system] is more of an accurate reflection of what’s going on in a district,’’ said Thomas Scott, executive director of the Massachusetts Association of School Superintendents. “We’ve been pushing for this for six years.’’

This year, the state is only providing data to schools. In the future, once schools become accustomed to the new system, the state plans to send the information to parents as part of their children’s annual MCAS report.

While the methodology behind calculating growth in scores is extremely complex, the state is presenting some of the information in a format familiar to many parents. It will plot their children’s rate of improvement on their MCAS scores on a chart similar to the one used by pediatricians to tell parents how their child’s height and weight compares with other children.

The system compares a student’s level of improvement on MCAS with other Massachusetts students who have performed at a similar level in previous years. The result is reported as a percentile, showing the percentage of students who have improved more quickly and the percentage who have not performed as well.

Schools, in turn, are measured by looking at the percentiles posted by their students and then taking the median, which is used to generate an overall picture.

The new system’s potential can be seen in a handful of school districts that began receiving the new scores last year as part of a pilot program.

In Winchendon, for instance, the district noticed that students were not making as much progress in the fourth grade as they did at other grade levels. This led leaders to reconsider their school configuration, which had students changing schools between third and fourth grade.

“It really for us affirmed what our internal assessments were showing,’’ said Brooke Clenchy, Winchendon superintendent.

The new system differs from another measurement the state developed under the federal No Child Left Behind Act, which also attempts to gauge a school’s progress in boosting student test scores. However, under that system, the state looks at the success schools have in increasing the percentage of students who score in the top two categories of the test, advanced and proficient.

At the O’Donnell School in East Boston, the state’s spotlight on its positive gains in student MCAS scores follows years of intensive work among its staff, its approximately 260 students, and their parents. The school has revamped the way it teaches reading and writing and has adopted a math program that strongly emphasizes using geometric blocks and other tools to solve problems - offering students who don’t speak English fluently another way to show teachers their understanding of concepts.

Students also use special software based on the state’s standards to answer math problems, allowing them to more closely track progress.

This year on the MCAS, half the students had math scores that grew as much as or more than 92 percent of their peers statewide. In English, the median growth percentile was 85.

The results add more context to the school’s overall scores in those two subjects. In math and English, about half the students scored advanced or proficient.

“We keep a laser light focus on how well our students are doing,’’ said Robert Martin, the school’s principal. “We have a school that is small enough that every single student’s score is statistically significant. That puts a lot of pressure on us.’’

Matthew Carroll of the Globe staff contributed to this report.