Scottish school pupils face being "taught less and learning less" this year unless urgent action is taken, the Scottish Conservatives have warned.
The party's Holyrood leader, Ruth Davidson, said schools were planning to cover less ground in subjects such as maths and English this year.
This was on top of the full term of classroom teaching that was lost during the school shutdown.
She called for extra tuition to be given to the most disadvantaged pupils.
And she said additional funding to help schools mitigate the impact of the pandemic must go directly to headteachers.
First Minister Nicola Sturgeon said the government had already introduced a "programme of improvements and reform" in education.
This included additional funding to councils to ensure pupils catch up with the education they have lost, and extra money for additional teachers to be recruited.
She added: "We are investing record sums in closing the attainment gap, we are supporting young people through this difficult period and we will work with the SQA to make sure that young people are supported to catch up".
BBC Scotland revealed on Tuesday that tens of thousands of pupils are currently off school - with attendance falling to 84.5%.
Ms Davidson told the Scottish Parliament that the loss of classroom learning during the lockdown had fallen hardest on pupils from the most disadvantaged backgrounds, whose communities had been "left devastated" by the virus.
She said thousands of pupils would lose further crucial classroom time by needing to self-isolate over the coming months.
She added: "It was revealed this week that the Scottish Qualifications Authority (SQA) has planned for schools to cover less ground in the curriculum in key subjects, including English and maths.
"Instead of building our pupils back up, this government seems content to accept second best.
"Less teaching, less learning, less knowledge this year for young people who already lost out last year. I don't think that is acceptable, and I doubt that many parents across Scotland will either."
She said parents expected the government to deliver the same standards of teaching as any normal school year, and called on the first minister to tell the SQA to "think again".
Ms Davidson said: "There are warnings ringing out about this school year already. There are parents, there are pupils, there are teachers who have all sounded an alarm about the SQA plans."
And she said the first minister had put a draft independence referendum bill in the programme for government, but not an education bill - despite previously claiming education was her top priority.
Ms Sturgeon responded by saying that the SQA will look closely at issues around the curriculum, and pledged that "we will listen very closely to the views that have been expressed".
She said: "It is important, particularly given the mistakes that were made - and I take responsibility for those mistakes - around the SQA results this year that we take time to make sure that we get that right while continuing to support young people through the ongoing virus situation."
The first minister said there had not been an education bill in the programme for government because it would have taken too long to pass it, with the government instead "doing all of the things that would have been in that bill without the need for education".
She added: "We will continue to make sure the investment is there.
"And we will continue to support teachers, schools, young people and parents not just to catch up the education that has been, unfortunately, lost during the pandemic, but to make sure that the objective of closing the attainment gap continues to be the priority".