Head teachers in England are being told to concentrate on the basics of literacy and numeracy and to improve classroom behaviour.
Ed Balls wants schools to focus on literacy, maths and discipline
The Schools Secretary Ed Balls is writing to all head teachers setting out priorities for the new school year.
Mr Balls says he wants to tackle the "devastating impact" of absenteeism and poor discipline.
He also says teachers should play a "key early warning role" in identifying "substance misuse and offending".
The letter from Mr Balls, being sent on Monday, will urge schools to focus on improving reading, writing and arithmetic - with an emphasis on those pupils who are failing to make progress.
The Conservatives have suggested that pupils who failed to reach the expected levels by the end of primary school should stay on to repeat the last year.
But Mr Balls attacked the proposal as "stigmatising the very children that we should be trying to do more to help" - and would mean increased class sizes in the last year of primary school.
"Early intervention with children is a fairer and more practical approach ," he says.
The Schools Secretary also wants an "unrelenting" emphasis on improving classroom behaviour.
"If the class has been disrupted by bad behaviour or by bullying, and if teachers need more powers, I'll give them those powers," he says.
The welfare role of schools has been expanded - and Mr Balls tells head teachers that they "play a key early warning role in identifying problems, like family breakdown, substance misuse and offending".