"This would mean time taken out of teaching and a return to pigeon-holing of young people at their most vulnerable age," Mrs Liddell told the association's annual meeting in Glasgow.
Michael Forsyth, the Scottish Secretary, seemed to suffer from "selective amnesia about the humiliation he suffered at the hands of Scottish parents when he tried to introduced mandatory testing in primary schools", Mrs Liddell said.
One of the lessons from south of the border, where grant-maintained schools had split the system, was that "if you hive off the best pupils, you will create a ghetto for the rest".
Ian Dutton, former director of education in the Borders, who has been recruited by the Government to promote opted-out schools, was "a glorified salesman at Pounds 45,000 a year". Mr Forsyth had "conjured up" Pounds 575,000 for building work at St Mary's primary in Dunblane in his own constituency, one of only two schools to opt out and a "pet project".
Money spent on administrating nursery vouchers could have provided an extra 1,800 places. A further Pounds 280 million had been wasted on local government reform, Mrs Liddell said. Every three and four-year-old in Scotland could be guaranteed a nursery place and 4,000 more teachers employed at a similar cost.
But Labour's plans for pupil "compacts" would, she confessed, take 10-15 years to introduce.