MALDEN — Massachusetts education officials have unveiled a new way of measuring the long-term performance of individual students, schools and entire districts on the MCAS exam.

Education Commissioner Mitchell Chester said the measurement model announced Tuesday provides a more complete way to assess student performance on the Massachusetts Comprehensive Assessment System exam, a requirement for high school graduation.

Rather than comparing a particular age group to its peers from previous years, the new "growth model" measures students and districts against themselves from year to year.

Under the model, low-achieving students who make significant progress are designated as experiencing "high growth."

Chester says the system allows educators to determine which teaching methods work best.