Education union NZEI are urging schools to boycott trials of a progress and consistency tool.
The Government is planning to make it compulsory for primary and secondary schools to use the proposed computerised consistency tool, known as PaCT, and says it will help teachers with their professional judgements with National Standards.
It is not a test, the Education Ministry says.
The ministry's deputy education secretary for student achievement, Rowena Phair said PaCT has been developed in response to concerns about consistency with National Standards.
She said the tool would help teachers to know how their students are progressing and what they might need to do to support each student.
"National Standards rely on the professional judgement of teachers, and PaCT is designed to support teachers to make those judgements. It is being developed with the teaching profession, for the teaching profession," Ms Phair said.
Teachers had asked for the tool, wanting more consistency and reliability about the overall judgements they make in reading, writing and maths, she said.
NZEI national president Judith Nowotarski said PaCT was the latest bid to give more credibility to National Standards.
"Teachers already know how well their students are doing. What they want is the ability to share new and effective teaching strategies and to access the specialist support many children that are struggling need. The Government needs to listen to the teaching profession and work with us to focus on how to lift students achievement, particularly amongst vulnerable children, rather than impose policies that have failed overseas."
NZEI are also urging all political parties to oppose the Government's plan to make PaCT compulsory.