First Minister Alex Salmond has been accused of a U-turn over a pledge that pupils would get two hours' PE a week.
Scots Labour leader Wendy Alexander said Scotland's obesity problems meant it was wrong to give up the plan.
Speaking at question time in Holyrood, Mr Salmond branded weekend reports of the claim "completely unfounded".
The Tories said plans for a new local income tax would hit students, while the Lib Dems questioned the government's efficiency savings plan.
Amid concerns that Scotland's place in the world obesity table was second only to the US, Ms Alexander asked: "Why, at the weekend, did the SNP government brief that it had agreed to break its manifesto promise to deliver two hours of quality PE for every pupil in Scotland?"
Mr Salmond retorted: "Wendy Alexander shouldn't believe everything she reads in the papers.
"Reports over the weekend that we intend to scrap this existing target are completely unfounded."
Ms Alexander accused the first minister of dodging the question and insisted the education spokesman for council umbrella group Cosla, an SNP member, had said: "We are moving away from the narrow targets such as two hours of PE."
Mr Salmond said investment in the area would go up by £40m over three years.
Scots Tory leader Annabel Goldie said working students, who are exempt from paying council tax, would be hit by ministers' plans to replace it with a 3p local income tax.
Branding it the "Nationalist tax on learning", she demanding of Mr Salmond: "What excuse is he going to give students for landing them with a new financial barrier?"
Mr Salmond said the government's plans aimed to help those on low incomes, adding: "It may come as news to Annabel Goldie that students tend to be on low earnings, if indeed they're earning anything at all."
Nicol Stephen, the Scottish Liberal Democrat leader, claimed ministers had still failed to make clear how they would achieve most of their £3bn efficiency savings plan.
He asked: "How does the first minister know that his list of efficiency savings over the next three years will not lead to cuts in public services?
"The truth is that most of his efficiency savings document is simply blank space."
Mr Salmond said they were a perfectly reasonable and achievable target, telling parliament: "We believe and will hold to that we can make these efficiency savings across the public sector with no compulsory redundancies."