Letter to Educators Explaining the Growth Model

September 10, 2010

Dear Massachusetts Educator,

For the first time, the Department of Elementary and Secondary Education is publishing MCAS growth data on the Parent/Guardian Reports for students in grades 4 through 8 and 10. I want to take this opportunity to explain the MCAS growth model and what it can tell you about student progress in English language arts and mathematics.

For over a decade, MCAS scaled scores and performance levels have answered the question, "How much has this student achieved compared to the state's grade-level learning standards?" The new growth score, called a Student Growth Percentile (SGP), answers the question, "How much did a student grow over the previous year compared to his or her academic peers?"

SGPs are percentiles (ranging from 1 to 99) calculated by comparing one student's history of MCAS scores to the scores of all the other students in the state with a similar history of MCAS scores. We refer to this group of all other students with similar score histories as a student's academic peers. In simple terms, students earning high growth percentiles answered more questions correctly on the spring 2010 MCAS test than their academic peers; conversely, students earning low growth percentiles answered fewer questions correctly than their academic peers.

Similar to MCAS scaled scores, SGPs require some interpretation. The following chart provides a way to think about student performance from both an "achievement" perspective and a "growth" perspective.

An example of a display of a student's SGP in English language arts included in the spring 2010 MCAS Parent/Guardian Report is shown below. The display also provides the school and district median SGPs for comparison.

The addition of student growth data to complement student achievement data gives educators and parents a more complete picture of how each student performed in the past academic year. For example, if students with a history of poor MCAS scores make above-average progress, they still may not be Proficient at the end of the year, but they will have a high growth score. Likewise, if students with a history of very high MCAS scores do not progress as far as their academic peers, they may still be Proficient or Advanced, but they will have a low growth score.

Massachusetts, along with several other states, decided to use this student growth percentile model because, compared to many other growth models, this model provides a fair way to evaluate the progress of students. Every student, regardless of his or her level of achievement at the beginning of the school year, has the same opportunity to grow at the highest or lowest rates.

The release of student growth scores is tied to a statewide effort to develop longitudinal data systems that will ultimately provide every educator with the opportunity to directly analyze student performance patterns. With this opportunity comes a responsibility to use the data appropriately to inform and promote effective teaching and learning. Our hope and expectation is that educators, parents, and others involved in the education of a student will use this data to discover and learn from what worked well, and what may not have worked so well, by reflecting on student growth trajectories and the possible factors that may be contributing to them.

Sincerely,


Mitchell D. Chester, Ed.D.
Commissioner of Elementary and Secondary Education

Last Updated: September 17, 2010