Educators say they're "stunned" by a collapse in the writing ability of boys, with latest national data showing boys in year nine are more than two years below where they should be and are substantially less capable than girls.

The alarm has been raised by Dr Damon Thomas, at the University of Tasmania, who said Australian boys in year nine have writing skills equivalent to being in year seven and the trend has been deteriorating since 2011 when they were equivalent to year eight students.