New teachers are often assigned low-performing math students. (AP photo)

LOS ANGELES (AP) – A new study shows inexperienced Los Angeles teachers are disproportionately more likely to be assigned low-performing math students.

The Los Angeles Unified School District study also found teacher effectiveness varies substantially.

The Los Angeles Times says top teachers are able to give students the equivalent to eight additional months of learning in a year compared with weaker instructors.

The study also found that teacher performance after two years is a fairly good predictor of future effectiveness.

Drew Furedi, who oversees the district’s teacher training, says he’s deeply concerned and describes the study as a call to action.

The study by the Strategic Data Project, which is affiliated with Harvard University’s Center for Education Policy Research, analyzed the performance of about a third of the district’s teachers.