Ofsted asks parents to rate schools on new website
Parents are to be encouraged to rate their children's schools on the Ofsted website.
England's chief inspector Christine Gilbert said where concerns were raised extra inspections would follow.
The Nasuwt teaching union said such a system would trivialise public accountability and the work of schools.
The plans come in a shake-up of school inspections in England, which will be streamlined and refocused on struggling schools.
The aim is to bring them in line with the coalition government's education policy. A consultation document on the plans is being launched on Monday.
But ministers have already announced changes to the inspection regime with a greater focus on schools in difficulty so that improvements are speeded up.
They have also ended routine inspections for outstanding schools, with inspections only resuming if a serious issue about a school is raised.
Ofsted chief inspector Christine Gilbert said: "From September we will be introducing a website where parents can tell us what they think about their school.
"If they're telling us things that really worry us, even if our assessments are fine, we will go in and inspect."
Parents at all schools would be able to use the website but it might be particularly useful for triggering inspections at outstanding schools.
The Ofsted survey would be linked to individual school pages on the organisation's website, and would feature a set of 10 questions related to teaching quality, achievement, behaviour and school leadership, Ms Gilbert said.
Parents would be able to respond anonymously or give their name, but they would only need an e-mail address to log their opinions.
The e-mailed response would automatically identify which school the parent was contacting Ofsted about.
Ms Gilbert said planning was in the early stages but that it was unlikely submissions would be made public or that free text would be allowed.
She said Ofsted had been working for some time on ways to feed parents' views on schools more easily into the inspection process.
These could be valuable in highlighting issues before they became a problem, she said.
Recalling an unnamed school in special measures, she said: "It was three years before the problems in the school started to show.
"If people were picking up the views of the parents than it would have been picked up earlier."
However, she also acknowledged that the results could easily be skewed either in favour of the school or against it by groups of parents.
Ms Gilbert said: "It's really to give them a sense of what's happening in a school - this is not a scientific model, it's an impressionistic tool, it's just another piece of information."
Chris Keates, general secretary of the Nasuwt teachers' union, said: "To hold schools to account on the basis of chatroom and internet gossip trivialises public accountability and the work of schools.
"Such a system would be open to abuse and manipulation and would therefore be an inappropriate and unreliable mechanism for triggering something as serious as inspection.
"The danger is that the inclusion of this suggestion in the consultation will detract from the serious debate needed about the fitness for purpose of the current inspection regime."
Christine Blower, head of the National Union of Teachers, said parents were generally very supportive of their children's schools.
"What is important for parents is that they have a voice in schools and that their views are taken seriously.
"It's not clear therefore why parents, who may have quite legitimate questions to which they seek answers, would choose this route.
"Parents will not want to be involved in triggering early inspections. To offer such an opportunity is unnecessary."