Standardised testing is "particularly problematic" for young children, an expert says.
Her comments come the day after the government announced it would introduce assessment for students beginning just 20 weeks into their first year.
Auckland University of Technology Associate Professor Ruth Boyask told Morning Report labelling children early as unsuccessful can become a self-fulfilling prophecy.
It was "particularly problematic" for young children, she said.
"It creates an environment where teachers are more focused on testing than they are on teaching, creating teaching to the test, placing pressure on children, and for very young children may be labelled at a very early age as being unsuccessful.
"The evidence from overseas is quite conclusive that that kind of testing tends not to measure what it intends to test, which is student learning."
Rather they were driven by external factors, largely a child's family situation, Boyask said.
She said achieving standardisation of the results would require significant investment.
"Wouldn't it be better to put that investment towards teacher's understanding of how to teach those children."
Mandating what teachers already do
NZEI Te Riu Roa president Mark Potter told Morning Report the announcement was essentially telling teachers to do what they were already doing and would not improve student learning.
"Schools assess and have always assessed, what we're saying is making mandated statements to schools to do something they already do is not a game changer.
"Just making mandating statements, it's almost Donald Trump like, you're not adding anything, it might be well-intentioned, but you're not adding anything to the game."
Potter said teachers were worried the same thing would happen as did with National Standards: "an obsession with testing means teachers start testing more and teaching less".
And he said it also had the potential to increase teachers' workloads when they were already struggling.
Teachers want more resources to help children who are behind, not to be "measuring them again and again".
'Good teaching the answer'
Labour's deputy leader Carmel Sepuloni told First Up supporting good teaching was the answer to improving education, not standardised testing.
"That focus on excellent teaching and the learning of our kids, and understanding kids are complex, that they come with different needs, that teachers have to be equipped with multiple tools and abilities in the classrooms and supporting them to get those."
It was also about resourcing, she said.
"At the budget we saw only enough money to keep the lights on... standardised teaching is certainly not the silver bullet."
Sepuloni said she wasn't confident in the government's promises that the results of the testing would not be used to make league tables to compare students and schools with each other.
"And quite frankly a little sick of the buzz words and sound bites that continue to be used by this government with respect to education."
