The Education Review Office has delivered what it says is a wake-up call for teachers and boards with a report highlighting schools' three most important shortcomings.
The report published on Wednesday pulls together the findings of 15 national reports on school practice published by the office in the past four years.
It says schools need to focus on the needs of individual students, provide a rich curriculum and use assessment results to plan their teaching.
It says schools could raise student achievement further if they addressed those issues.
The report says problems the review office identified four years ago are still evident in schools and some principals are too soft on teachers.