The Government has performed a U-turn on plans for Leaving Cert students to attend school for three days each week.
Final-year students will now engage in remote learning for five days a week until the end of January.
It comes after the ASTI teachers' union said they would not comply with the directive amid concerns over safety for students and staff.
It had directed its members not to comply with plans for Leaving Cert students to attend school for three days a week.
The union, which represents more than 17,500 teachers, said it was not consulted about the plan to partially reopen and had not received sufficient assurances that "schools are sufficiently safe" for students and teachers.
At an emergency meeting on Thursday, the ASTI standing committee decided to direct its members not to co-operate with the arrangements announced by the Minister for Education for in-school teaching.
The union said it would engage in remote teaching/learning from Monday January 11.
President Ann Piggott said: "The ASTI has repeatedly sought sufficient assurances that schools are 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.
"We engaged with the Department of Education and with public health officials today. Unfortunately, the assurances we sought have not been forthcoming."