The INTO is calling for the government to set up a public awareness campaign to help stop the spread of Covid-19 in schools.
The HSE's testing and tracing system is under pressure after 28 thousand children presented for PCR tests in the past seven days.
Many pupils have been told to stay at home, after Covid outbreaks in classrooms led to a large number of 'close contacts'.
General Secretary of the INTO, John Boyle says teachers are reporting some children coming to school with symptoms.
"With the crisis that has emerged int he last week we want to keep the schools open safely.
"People just have to have another think about the symptoms, the symptoms have changed. There are common and uncommon symptoms, that's a difference from last year now that we have the Delta variant.
"I think it will be necessary for a ramped up campaign so that everybody understands that if you are to keep your schools open safely. you have to cooperate with the public health advice that is there at the moment."
