The Education Review Office has called for improvement at New Zealand's biggest school, Te Aho o Te Kura Pounamu, formerly known as the Correspondence School.
The review office says it has found the same serious concerns about poor student achievement and participation that it raised four years ago.
Sixty-one percent of the school's 4000 fulltime students are at risk, but the review office says the school's learning model is not suitable for many of those students because they lack the skills and motivation to work by themselves.
The review says the school is not engaging most of its Maori students and staff morale is low.
The ERO says a robust improvement programme is needed, but chief executive Mike Hollings says the school is improving.
Mr Hollings says it is working more with other organisations to support at-risk students and the results from that work are very good.
The review says there is no evidence that Mr Hollings was properly appraised in 2012.