Teachers’ unions said educators had not been given enough time to respond to rules issued earlier this month.
Northern Ireland’s chief medical officer Dr Michael McBride has insisted it is safe to return.
Strict social distancing between children may be relaxed if there are hygiene measures in place.
Face coverings are not mandatory for routine use by pupils, Stormont’s Department of Education has said.
Stormont’s education minister Peter Weir said: “Schools are not unsafe places for children and they are not unsafe places for teachers either.
“Very, very few, if any, children will come to harm as a result of attending school, but there is evidence of the long-term harm to children’s education, life opportunities, mental health and wellbeing from not attending school.
“There is clear unequivocal evidence that children are less likely to catch Covid-19, where they do most of them will have mild to moderate symptoms and in most cases they will make a very full recovery.
“There is a very, very low – indeed an incredibly low incidence – of serious disease within children and they are also less likely to transmit the virus.”
Schools closed in March to help contain the spread of coronavirus.
Pupils in Primary 7, Year 12, Year 14 – whose preparation for exams was disrupted by the lockdown – and all vulnerable children are due to return to classes on August 24.
All other pupils will begin the new school year on the week beginning August 31st after months of variable levels of home schooling.
Official guidance recommends the formation of protective bubbles for primary school children and pupils in years 8-10 in post-primary schools.
The department said interactions between different year groups of older pupils should be limited.
Parents, pupils and their teachers face the added strain of uncertainty over the future, Mr Weir has acknowledged.
A total of £42 million (€46.5 million) has been spent on re-starting schools safely.
A package of measures for the first term covers the cost of substitute teachers and other school expenditure, personal protective equipment, school well-being, transport and special educational needs.
Mr Weir said: “I fully recognise the stresses felt by teachers, parents and pupils due to the ongoing disruption and uncertainty regarding the future.
“My key priority has always been to ensure all of our children and young people return to school on a full-time basis, as soon as it is safe to do so.”
