Sturgeon: 'No excuses' for Scots school performance
First Minister Nicola Sturgeon said she will make no excuses for the poor performance of Scottish schools in an international survey.
Scotland recorded its worst scores in the OECD's Pisa rankings in 2015.
Opposition politicians said Scotland was going "backwards" in reading, science and maths under the SNP.
Ms Sturgeon took responsibility for the results, which were "not good enough", but said they underlined the case for her educational reform plans.
The first minister also defended the Curriculum for Excellence (CfE) as "the right way forward" for Scottish schools in the face of criticism.
During the weekly session of questions to the first minister, Scotland's decline in international rankings was brought up by opposition parties.
Scotland was within the average banding for the Organisation for Economic Co-operation and Development, but was placed lower in all three subject areas than in any previous Pisa survey.
Asked who she would seek to blame for the results, Ms Sturgeon said she herself took responsibility.
She said: "I take responsibility on behalf of the Scottish government for the performance of Scottish education.
"If anybody thinks I'm going to stand here and give any excuses, they're wrong. There's lots of other evidence I could cite about Scottish education, but I'm not going to do that today, because the results of the Pisa survey are not where I want us to be.
"They are not good enough. And I'm determined that we take the action that will lead to improvement."
Ruth Davidson said the SNP had been in government for 10 years and had not managed to sort out education, and added that her party could potentially withdraw their support for the current curriculum system.
She said: "The single biggest education reform under this SNP government has been Curriculum for Excellence, and nobody here can simply brush aside the fact that since it has come in, standards have fallen.
"So I'm telling the government today, that our ongoing support for CfE cannot be taken for granted.
"I believe that this entire project should be put on probation. And there's a simple question I ask in all sincerity - if standards are going down because of it, why are we sticking by it?"
Ms Sturgeon replied by quoting Tory education spokeswoman Liz Smith, who she said had recently described the principles behind CfE was being "absolutely right" and adding there was "unanimous agreement" about it at Holyrood.
Ms Sturgeon added: "I believe Curriculum for Excellence is the right way forward."
She said the government was acting on OECD advice to close the attainment gap, put in place a measurement framework for schools, simplify the curriculum and empower school leadership.
She added: "There are hard, concrete, tangible actions.
"I know the opposition will want to criticise over the Pisa results, and I can have no complaint about that. But what I think is most important now is that we all get behind these reforms, because these are the reforms that will lead to the improvement we want to see in Scottish education."
Scottish Liberal Democrat leader Willie Rennie also asked the first minister about the Pisa scores, spending some time listing all of the countries ahead of Scotland in the rankings.
He said: "Scotland used to have one of the best education systems in the world, now we have dropped behind all of those countries. After 10 years of SNP rule, we are not even as good as England any more. What went wrong?"
Ms Sturgeon said she would not "rise to the bait" of a political row over education, repeating that the Pisa figures were not where she wanted to be.
She pointed out that all the reforms proposed by the Scottish government had been opposed by the Lib Dems.
Mr Rennie said the first minister was "incapable of providing any explanation as to why Scottish education has slipped so far", calling for "transformational investment" in schools.