On top of that, only 17 per cent of students from low decile schools reached the expected standard - a drop of 6 per cent since the last study in 2018.
Pacific students fared the worst with only 15 per cent of Year 8 students at the expected level - 9 per cent fewer than 2018.
Māori student achievement in Year 8 dropped 6 per cent meaning only 21 per cent of students passed.
The study found 37 per cent of girls reached the expected achievement level in Year 8, however, that was a 6 per cent drop since 2018.
Year 4 student achievement, also measured by the study, is much the same as in the previous report at 82 per cent. Again Pacific and low decile students fare worst, both at 63 per cent.
Education Minister Jan Tinetti said given the disruption caused by Covid, it was a “real credit” to the efforts of teachers and students that the overall results were not negatively affected.
“The results are promising for Year 4 but concerning for Year 8, particularly for Māori and Pacific learners, and girls,” she said.
“More work is needed to lift achievement levels, which is why the Government has an extensive work programme under way. This includes changes to strengthen the national curriculum and its implementation at the local level curriculum to be clear about what learning needs to occur, when and how, so that all ākonga (students) can succeed.”
Tinetti said the work was a priority for the Government, especially in maths and literacy, and she was confident it would help resolve the issue.
National Party education spokeswoman Erica Stanford slammed the results as “extremely damning” and said the study showed we were not setting our children up for success at high school.
She said the results were terrible for the “kids who need our help the most to change their lives and change their circumstances”.
“These are the kids that Jacinda Ardern talked about closing the equity gap - about making sure that we’re ending child poverty.
“Well, actually, if you want to do that, you need to make sure that the kids in low decile schools and our priority learners are achieving much better and under this government, they are achieving much, much worse.”
Stanford said a good standard of mathematics was important for improving lives and future income and we were letting down the students who needed it the most.
National had already promised to introduce a curriculum that clearly laid out the core content knowledge every year to make sure all students get the same core content knowledge every year, she said.
Stanford also said investment was needed to make sure teachers had the resources to teach mathematics.
Ministry of Education Curriculum Centre leader Ellen MacGregor-Reid said they were firmly focused on improving results and addressing what is occurring for particular groups of students.
She said the refreshed mathematics curriculum and the common practice model being developed would be more clear about the most important learning and how best to teach it.
The ministry was also developing resources and professional development to support teachers to implement the changes.
“We know that the education system has not always served Māori and Pasifika students well. Alongside the Literacy and Communication and Maths Strategy, cultural capability continues to be a national focus for professional learning and development for teachers,” MacGregor-Reid said.
As for lower socio-economic areas, she said the new equity index which replaced the decile system this year aimed to better resource those schools and help lift achievement.
“This is the final cycle of NMSSA. It is being replaced by a new curriculum insights and progress study, which will provide greater insight more frequently into how young people are progressing across the curriculum, with a focus on maths and literacy,” she said.
Amy Wiggins is an Auckland-based reporter who covers education. She joined the Herald in 2017 and has worked as a journalist for 12 years.