Scotland's exams agency, the SQA, says it is working urgently on the emergency arrangements to help teenagers who should have been sitting exams in the coming weeks.
This year's school exams - including National 5s and Highers - have been cancelled for the first time ever.
The SQA says it is still working out exactly how to award grades "in as fair a way as possible".
The broad plan is to use supporting evidence such as coursework and estimated grades from teachers to determine what each candidate gets.
Since Friday afternoon, all schools in Scotland have been completely closed to students.
Over the weekend the government made it clear no senior students were to go in to school to finish coursework. Some schools and councils had been hoping this would still be possible.
SQA chief executive Fiona Robertson said: "This is an unprecedented situation for us all, and circumstances are rapidly changing. With every change in circumstances, we continue to consider how best to recognise learner achievement in as fair a way as possible.
"Please be assured that everyone here at SQA is fully committed to working... to deliver for Scotland's young people. Thank you for your patience and continued co-operation."
Some candidates working for their Highers and Advanced Highers may already have completed their coursework. The SQA says this can still be used by teachers and lecturers to help work out estimated grades.
The SQA says it has already received coursework for some National 5 subjects. It has now contacted coursework markers to confirm the arrangements for marking.
However National 5 coursework which was due to be submitted in April and May will not now be marked.
Ms Robertson added: "We will provide further details on the estimation of grades, that we will need from teachers and lecturers to inform certification, and fuller details of our approach to certification, as soon as possible."
The hope is that candidates will still get their grades by 4 August - this should have been exam results today.
The arrangements are of particular importance to candidates hoping to get the grades they need to meet a conditional offer of a university place.
Universities say they will work closely with others to make the emergency arrangements work.
'Pressures and worries'
The universities themselves are continuing to confirm their own arrangements for current students.
The University of Strathclyde became the latest to say summer graduation ceremonies would not take place.
Strathclyde also confirmed Year 1 and 2 students would be able to progress to the next year of their studies without final exams.
Meanwhile the teaching profession's governing body GTC Scotland - says it will help put together resources to help teachers look after their wellbeing.
It said: "It is important that throughout this time all education professionals care for their mental health and wellbeing.
"Pressures and worries can build up to a point where they have a detrimental effect on wellbeing, which in turn impacts teachers' ability to do their job.
"In the current circumstances, it can be challenging to balance wellbeing with managing uncertainty and changing expectations."