Minister for Education Jan O'Sullivan has said the ball is in the unions' court as they prepare to stage a one-day strike over planned reform of the Junior Certificate.
The strike will see 720 secondary schools close tomorrow and it will result in 350,000 second-level students staying at home.
The Department of Education said it has moved as far as it can to allay the teachers' concerns.
Writing in the Irish Independent today, Minister O'Sullivan said the Association of Secondary Teachers of Ireland and the Teachers' Union of Ireland must understand that negotiation involves compromise.
She said that having moved 60% of the way towards teachers' demands, she is now being told that they will do business if she moves another 40%.
Ms O'Sullivan said this is not negotiation.
Unions have said they are resolute and united in their opposition to plans for Junior Cycle reform.
The unions are upset by plans for pupils to be assessed by their own teachers for 40% of their work instead of an external examiner.
Teachers who do not support the strike may report for work tomorrow so as not to be docked a day's pay.