Schoolchildren across England are "on strike" in protest at controversial tests for six and seven-year-olds.
The action comes after more than 40,000 people signed a petition supporting a boycott of Year 2 Sats by teachers.
The Let Our Kids Be Kids campaign has organised the day of action in protest at children being "over-tested, over-worked and in a school system that places more importance on test results and league tables than children's happiness and joy of learning".
Imagine being told you suddenly needed to do two years' work in one; that's what's being asked of every child this year. #KidsStrike3rdMay
-- Julie Wilkinson (@mrsmooshoes) May 3, 2016
The petition added: "We want our kids to be kids again and enjoy learning for learning's sake, not for Ofsted results or league table figures. Bring back the creativity and the fun - say goodbye to repetition and boredom."
Sats are taken by children aged six or seven in Year Two and then again in Year Six, aged 10 or 11, before a third set in Year Nine, aged 13 or 14.
Parents and children are organising fun and educational activities during the protest all over the country.
-- Rowena Kay (@rowena_kay) May 3, 2016
Got Dollop off school today as we're joining in #KidsStrike3rdMay. Off to the museum & art space soon, and we've already talked politics.
-- Vicki (@BoysBehaviour) May 3, 2016
Ben Ramalingam from Brighton - where lots of concerned parents are meeting in Preston Park - is keeping his five-year-old son off school in protest at what he says is a hothouse culture that has made young children stressed.
-- Jeremy Burton (@ghostyhead) May 3, 2016
-- Amy Hall (@amyrhall) May 3, 2016
He said: "Our kids are being left disengaged and stressed. Kids who previously loved school are now refusing to go.
"There are a number of people who are saying this has the potential to turn into not just an educational crisis, but a mental health crisis."
Education Secretary Nicky Morgan warned that missing school even for a single day would be "harmful" and called for those behind the "damaging" campaign to reconsider.
In a speech on Saturday, she said: "To those who say we should let our children be creative, imaginative and happy - of course I agree, both as a parent and as the Education Secretary.
"But I would ask them this: how creative can a child be if they struggle to understand the words on the page in front of them? They certainly can't enjoy them.
"What are the limits placed on a child's imagination when they cannot write down their ideas for others to read?"