Studying from home was universal among Irish students last year.
Teachers who are members of the main secondary school trade union have been directed not to co-operate with the Government's plan for the partial reopening of schools to facilitate Leaving Certs on a three day week.
Association of Secondary Teachers in Ireland (ASTI) has directed its members said in a statement.
"The ASTI Standing Committee met this evening to discuss the announcement by the Minister for Education Norma Foley that special schools, special classes and specialised settings will be fully open from Monday 11 January and that Leaving Certificate students will receive in-school teaching provision for three days each week with all other students to be supported to learn remotely.
"The ASTI was not consulted before this announcement. The ASTI has not been provided with the necessary assurances that schools are sufficiently safe for students and teachers at this time, in the context of the new variant of Covid-19 circulating in the community and the alarmingly high numbers," IT SAID.
ASTI said its Standing Committee decided to direct teachers "not to co-operate with the arrangements announced by the Minister for Education for in-school teaching".
Instead, teachers have been instructed to carry out remote teaching/ learning provision from Monday.
The union has received a "high number of communications from second-level teachers expressing their concern that the movement of more than 80,000 individuals to and from schools is not essential and poses a great threat to public health in the current context".
The Government says schools are safe and wants Leaving Certs to go back to school on a three day week from January 11. It says it wants to hold the Leaving Cert in a 'traditional' way this summer.