Children in 3rd class and above could be refused entry to primary school from today if they don't wear face-masks.
However schools are being allowed flexibility in how it's applied in the first couple of days.
The measure's part of new Department of Education guidelines to combat rising Covid infection rates.
Suzanne Connolly, from Barnardos, has highlighted the impact the new measures may have on children's development.
"It's going to be far more difficult for children to communicate through a mask in school and to develop confidence in verbal communications."
She's says it's particularly important that young children's educational, social and emotional development is monitored.
Meanwhile General Secretary of the Irish National Teachers Organisation, John Boyle, is asking parents to support the new measures.
He said people those who don't are defying public health advice and put staff and fellow pupils "in jeopardy"
The government also wants less indoor social mixing by children for the next two weeks in a further effort to curb cases.
Covid rates among 5 to 12 year olds have increased by 47 per cent in the space of two weeks, with over 11,700 in the fortnight to last Sunday - compared to less than 8,000 in the previous two weeks.