The National Union of Teachers' outgoing leader has condemned the government for "turning our schools at all levels into exam factories."
Christine Blower, used her final speech as general secretary to tell the union's conference in Brighton that the "excessive focus on exam results" is "bad for pupils, bad for teachers and it is clearly the antithesis of what NUT members believe to be a good education".
She also described the new baseline tests - for four and five-year-olds - as a "fiasco".
On Sunday, teachers carried an emergency motion calling for a potential ballot for a boycott of the baseline, and KS1 and KS2 tests “at the most appropriate time”.
Ms Blower said: "I want to wholeheartedly congratulate the schools which chose not to put children and teachers through it and let’s encourage very many more, perhaps all, not to engage in the voluntary but unacceptable activity next academic year.
"The notion of a school readiness check is beginning to take hold in some places. This is a notion that can be a somewhat reductionist checklist covering such attributes as “Can hold a pencil”, “Can sit still on a chair” and “understands the word No”.
"These may all be worthwhile things to know about a rising 5 year old but they cannot be, as baseline couldn’t be this year, an accountability measure for schools once those children reach the age of 11."
A recent survey by the NUT, of more than 5,200 primary teachers in England, found that almost nine in ten primary teachers believe education secreatry, Nicky Morgan, should cancel national tests due to be taken next term.
More than 90 per cent of teachers at key stage 1 and key stage 2 said much of the material in the new spelling, punctuation and grammar tests – known as SPaG– was inappropriate for the age groups being tested.
Ms Blower called the government's guidance on exclamation marks for the SPaG assessment "tortuous nonsense" which had caused "such anger and dismay" to many teachers.
She added: "The issues of both the KS1 and KS2 assessment would be laughable if they weren’t so serious for our members and the children whom they teach – and, of course, the children’s parents and carers."
Ms Blower, who will step down in May, will continue working with the union part-time on international affairs.