Parents are being urged to keep their children off school for a day
Children in Britain are to strike for the first time in protest at being "over-tested" and "over-worked" by what parents say is an exam-dominated school curriculum.
More than 40,000 parents have signed up to the action, describing the "testing regime" for SATs as "shambolic".
The Key Stage 1 testing for six and seven-year-olds has been made tougher this year in an attempt to drive up standards.
Parents are being urged to keep their children off school for "a day of educational fun instead" and a website run by the Let Our Kids Be Kids campaign includes posts from hundreds of groups or parents who say they will have their children take part in another activity rather than attending classes.
The campaign, which is coordinating the kids' strike, has written to British Education Secretary Nicky Morgan calling for an "end to SATs now".
The letter said: "Do you want your legacy to be the confident cancellation of unneeded and unnecessary SATS, showing you are listening to your electorate and the teachers you claim to support...or the overseeing of a shambolic testing regime desperately unwanted by millions of people to the point that this country saw its first open parent revolt?".
"You have the power to stop these tests. Now. Our children, our teachers and our schools deserve better than this".
Concerns have been raised about the tougher SATs, including those from head teachers who say they will see thousands of schools failing to make the grade.
Speaking at the National Association of Head Teachers' annual conference in Britain at the weekend, Ms Morgan urged those in charge of the "kids' strike" to think again - telling the conference that keeping children home was "damaging".
She said: "Keeping children home - even for a day - is harmful to their education and I think it undermines how hard you as heads are working".
She added "more rigorous" tests of young children would help to address the achievement gap in functional literacy between England and Korea, Singapore and Ireland.
Shadow UK Education Secretary Lucy Powell said she did not condone the strike but said that ministers had "ridden roughshod" over teachers' and parents' concerns.
She added: "Ongoing assessment is really important to help teachers and parents support their children's education and to close any gaps in knowledge so all children can do well at school".
"However, the way this government has handled the assessment regime means that parents and teachers are lacking confidence in school tests and the assessment system is being undermined".