Pupils should face fewer tests and should be given more time to develop at their own pace, the Archbishop of Canterbury has said.
Dr Rowan Williams says children must not be overloaded
Dr Rowan Williams said, while it was right to make education an accountable business, testing had produced a "hurried culture" of rounds of tests.
Speaking on Radio 4's Today programme, he also expressed concern that children were being turned into consumers.
The Department for Education stressed that tests were here to stay.
But Dr Williams told the Today programme there should be "more space" in the education system and schools should have time to explore the "creative", if not productive, aspects of human growth.
He said the education system may have overloaded children with exams.
"I think we very rightly wanted to make education an accountable business.
"I think the way we've gone about it has produced a hurried culture where you've got to make absolutely sure you've got children through the next round or over the next hurdle.
"It is a very competitive world but if they're not going to be crushed and mangled by that competitive world they've got to have some inner resources."
However, the government stressed that tests were "a non-negotiable part of school reform".
"They provide valuable objective evidence in the core subjects, helping inform further improvements to teaching and learning," a DfES spokesman said.
Children as consumers
Dr Williams also said he feared that children were being turned into consumers at too young an age.
"One of the examples of a hurried culture is hurrying to get children into the market, to get them in to the adult world rather than giving them the time they need."
He said children needed "a sort of latency period" to grow and explore at their own rate.
"We want children to be consumers as soon as we can get them to be consumers.
"We want them to be involved in the adult world of purchasing, marketing and all the rest of it.
"I've been worried about that for quite a long time. It's not an entirely new thing but it does seem to be getting more marked."