The Teachers’ Union of Ireland (TUI) has said that a funding package to allow schools fully open by the end of August must be kept under review.
The plan is expected to be announced later on Monday after details were discussed over the weekend.
Enhanced cleaning regimes, investment in school buildings and more substitute teachers are just some of the measures planned to reassure people that school will be a safe place for their children.
The reason additional teachers are being sourced is because staff are being advised not to come in if they display symptoms of the coronavirus.
It is believed lunch breaks will be staggered, but masks will not be essential in classes.
Primary school pupils will also be sectioned off into pods of between four and six children.
It is thought support from unions will be vital to its success.
The TUI has said ensuring the health and safety of students, teachers and the wider community must remain the priority.
General-Secretary John MacGabhann said: "At all points in our engagements with the Department of Education and Skills on the re-opening of schools, we made clear that the overarching priority must be the health and safety of students, teachers and others in the wider community.
"The clear preference of our members has always been, as much as is possible, a return to face-to-face, school-based learning, and this is particularly important for those students who have been disadvantaged by the online environment of recent months.
"However, schools are busy and dynamic workplaces and the social distancing and other requirements set out by the public health authorities must be adhered to.
"Clearly, significant investment in updating infrastructure is required, along with an enhanced teaching allocation and administrative supports to ensure that arrangements consistent with public health advice can be put in place and to provide against circumstances in which schools find themselves short-staffed because of necessary absences."
"If it becomes clear that the initial budget set aside for the re-opening does not prove adequate, further resources will need to be made immediately available.
"In addition, we expect ongoing engagement with the department to address arising issues and matters that have yet to be finalised, including arrangements in respect of students and teachers who may not be able to return to the workplace because they are in high-risk categories."
A lack of clarity over whether the full re-opening would actually happen has led to growing anxiety among parents and pupils.
Targeted supports for students with special needs are also thought to be included in the planned €300m package.
The Cabinet will be briefed on the details before its publication.
Schools have been shut since March 12th due to the COVID-19 pandemic.
But speaking on Friday after meeting Education Minister Norma Foley, Taoiseach Micheál Martin said the plan would be "a very comprehensive set of measures that will enable schools to open fully - but also in a resilient and robust way".
Minister Foley said schools will be back to normal for the new term.
"The objective is a full re-opening of the schools, yes indeed - all students on campus, all teachers on campus", she said.