Sinn Fein has stuck by its anti-selection position when it comes to the transfer of pupils from primary to secondary education.
The first stage of tests is held by Grammar schools across Northern Ireland on Saturday.
Around 7,000 pupils will sit the tests which have been compiled by the Association of Quality Education to replace the now defunct 11 plus.
Next Saturday, a consortium of Catholic Grammar Schools will introduce their test option to around 6,000 pupils.
'Unjust'
Sinn Fein has insisted the testing of 10 and 11-year-olds has no proven educational benefit and presents numerous educational and social disadvantages.
"I would call on all those who are genuinely opposed to the socially unjust practice of academic selection to recommit themselves to ending it, not by accommodating further testing on the false promise of 'give us more time and we will change'", the party's Education spokesman John O'Dowd said.
"The facts are the grammar lobby has had 50 years to change and they have continually held onto their unjust system."
"I would also like to pay tribute to the silent majority, the pupils who will not be sitting a test, who will transferring into a Post primary school which teaches the exact same curriculum as Grammar and offers access to the same level of qualifications as grammar schools."
The Ulster Teachers' Union has warned those behind the tests to brace themselves for the "fall-out" of this year's exams.
Spokeswoman Avril Callaghan-Hall said: "There's probably mixed attitudes to it.
"My concern is that we provide the best possible education for all our young people and I don't think testing them at the age of 10 or 11 is the way to do that."
This year the pupils will sit the tests in grammar schools, instead of their own primary schools.
But Belfast Royal Academy head teacher Moore Dixon said staff had done their best to ensure the day runs smoothly.
"In each room, there will be children from the same primary school, so they'll have familiar faces around them. Provided there are other children from their primary school, they'll all be with ones they know," he explained.
© UTV News