That's according to new public health advice, published by the Department of Education.
In primary school, one metre should be kept between children from third class onwards.
Social-distancing will not be essential for the first four years of schooling.
Secondary pupils will be asked to keep two metres apart - but if that's not possible, one metre is sufficient.
Dr Martin Daly, a former president of the Irish Medical Organisation, says there will be concern about the advice.
The Association of Secondary Teachers of Ireland says it notes the advice from public health officials.
It says a lot of work needs to be done to determine how many secondary school students will be able to be taught at one time.
