The Kenya National Union of Teachers (Knut) has stepped up its opposition to the new curriculum and poked holes in the review led by the Education ministry.
Knut on Thursday asked its members not to teach and examine the competency-based curriculum.
Instead, Knut Secretary-General Wilson Sossion told teachers to revert to the old curriculum, saying the review breached law.
The new curriculum policy launched by Education Cabinet Secretary George Magoha on Wednesday, he said, did not involve all stakeholders.
The Knut chief, who is also a nominated MP, hit out at Prof Magoha, accusing him of “being arrogant and refusing to listen to other Kenyans”.
"You need time to train teachers at pre-service level and not teachers who are already in service. The trainers do not understand the curriculum,” he told reporters in the capital Nairobi.
Mr Sossion said teachers are not adequately trained to teach and examine the new curriculum that de-emphasises exams.
He said there is no agreement on assessment of learners and that classrooms in public schools are not enough to accommodate more pupils.
The union also trained its guns on teachers employer the Teachers' Service Commission for siding with the ministry.
TSC, Mr Sossion said, should be reduced to a department under the ministry because “it is a burden to Kenyans”.