Not all pupils will return to school at once when coronavirus restrictions are eased, Education Minister Kirsty Williams has said.
Schools have been closed for five weeks, apart from for key workers' children and vulnerable pupils.
Ms Williams said she did not expect schools to "suddenly open" for all.
She said there would be "a phased approach in allowing more pupils to return to school", based on five principles.
Ms Williams, who has previously said schools may not open until September, said school provision would "gradually adapt and extend further during the next phase in line with changes to the current restrictions outlined by the first minister last week".
On Friday, Mark Drakeford said ending lockdown would be "like a traffic light in reverse", with a move from red - some "careful and controlled" relaxation - to green, which would be "much more like the lives we had before the crisis hit".
The five principles for returning to school
The safety and mental, emotional and physical wellbeing of students and staff
Continuing contribution to the national effort and strategy to fight the spread of Covid-19
Having the confidence of parents, staff and students - based on evidence and information - so that they can plan ahead
Ability to prioritise learners at key points, including those from disadvantaged backgrounds
Having guidance in place to support measures such as distancing, managing attendance and wider protective actions.
Ms Williams said the latest information on the rate of transmission of coronavirus "allows us to be hopeful, but still requires us to be cautious".
"We will only enter the next phase when the evidence and advice suggests that it is the right thing to do".
She said schools, pupils and parents would be told of any changes "well in advance" to allow them to plan ahead.
"Schools will not immediately return to operating at full capacity," she said.
"It will be a phased approach and I do not expect schools will suddenly open for all pupils, from all years, all week."
The Liberal Democrat AM for Brecon and Radnorshire said schools would not all open at once
Calling school staff and childcare workers "national heroes", she said they would prepare schools for "a range of scenarios for the foreseeable future". "However unlikely, we must prepare for an eventuality that requires schools to reduce operations at specific future points", she added. Assembly members will get the chance to question Ms Williams when she addresses the children, young people and education committee on Tuesday.