A major study has found no change in children's average maths achievement but the gap between rich and poor has grown for Year 8s.

The National Monitoring Study of Student Achievement assessed 4000 Year 4 and Year 8 children in term three last year.

It found pupils' average achievement was not statistically different to results from the previous assessment in 2018.

However Māori and Pacific children in Year 8 and girls in Year 8 did slightly worse on average than in 2018.

Similar to previous rounds of testing, 82 percent of Year 4 children met curriculum expectations for maths but among Year 8s only 42 percent did so, a decrease of three percentage points since 2018.

The assessment found the gap between rich and poor had reduced since 2018 among Year 4s, but increased for Year 8s.

"At Year 4, the difference in average scores for students from high and low decile schools was 17 units. At Year 8, the corresponding difference was 21 units. The difference at Year 8 is equivalent to two and a half years of 'progress'. It means, that on average, students from low decile schools were achieving at one curriculum level below their counterparts in high decile schools," the report says.

In 2018, the difference between high and low decile schools was 20 units at Year 4 and 18 at Year 8.

The report says eight units represented about a year's progress in maths.

It found boys' average score in 2022 was three units higher than girls in Year 4 and five units higher at Year 8.

There were also differences in achievement between different ethnicities.

"On average, non-Māori students scored higher than Māori students by 11 scale score units at Year 4 and 14 units at Year 8. Non-Pacific students scored higher, on average, than Pacific students by 13 scale score units at Year 4 and 17 units at Year 8. On average, Asian students scored higher than non-Asian students by 13 scale score units at Year 4 and 16 units at Year 8."

The assessment included questions that ranged from adding and subtracting two-digit numbers to creating pie charts and explaining how to convert between grams and kilograms.

Health and PE results hold steady

Year 4 and Year 8 pupils' performance in the NMSSA Health and Physical Education assessment last year was similar to the previous assessment in 2017.

More than 3600 students were assessed on critical thinking with questions that ranged from factors that affected wellbeing to explaining strategies to promote wellbeing.

It found 87 per cent of Year 4 pupils and 33 per cent of Year 8 pupils were performing at the curriculum level expected of their age group, about the same as in 2017.

Girls scored higher than boys on average and students from high-decile schools scored higher on average than those from lower-decile schools.

An assessment of physical tasks with more than 1240 students showed a very slight drop in achievement of about two percentage points since 2017, though one obstacle course-related task showed a big drop in achievement for both year groups.

-John Gerritsen/RNZ.