A snap announcement from the Welsh Government to allow all children back to school before Easter has lead to a warning of 'chaotic scenes'
Ministers in Wales had previously insisted that pupils of exam years only will return to secondary schools, along with older primary pupils, from March 15.
But on Wednesday it announced that children in years seven to nine will return for "check-ins".
The Association of School and College Leaders warned that giving schools just eight days to prepare for the change of plan risks the return to school “descending into chaotic scenes”.
Headteachers had a mixed response with Stephen Garthwaite saying the proposals were badly communicated and showed a lack of regard for school planning.
But the headteacher of Ysgol y Grango in Wrexham, said he wanted to see pupils back.
He told Wales Online : “There was no prior warning of this development, and this represents poor communication from Welsh Government and a disregard of the logistical implications for schools.
“I have read the full operational guidance and the details about the years seven to nine wellbeing days are vague to say the least.
"There is little detail as to what these days/sessions entail."
Julian Kennedy, head of Ysgol Dyffryn Taf in Carmarthenshire, said he was surprised by the announcement which now poses 'a logistical challenge'
"Whilst we will obviously do our best to bring as many pupils on site safely as we can, the logistical challenges are huge, when considered in the context of government guidance, especially the maintaining of social distancing between age group bubbles," he said.
Eithne Hughes, Director of the Association of School and College Leaders, agreed with their concerns.
She said: "The principle of bringing back children in years seven to nine for a few hours to check that they are well both physically and mentally and looking forward to returning to school after the Easter holiday is a great one.
"What isn’t so great is the idea that they should do so along with hundreds of other older pupils on the same day, adding more strain to an already strained system."
Neil Butler Nasuwt national official for Wales said schools must now ensure that there is strict social distancing for staff and learners.
He added: "This change is unnecessary and may cause enormous difficulties in schools.
"It will bring added pressure they can do without as they struggle to maintain a safe working environment."
But Hugo Hutchison, headteacher of Monmouth Comprehensive School, is “delighted” with the change.
He said: "Although there is little time to plan, we have learnt to be agile and to respond quickly to challenging events."
Armando di Finizio, headteacher of Cardiff’s Eastern High, agreed saying: "It gives us the opportunity to focus on those in exam year groups and to prepare the whole school for a summer term that has to be centred on repairing, refocusing and rebuilding."
David Blackwell, headteacher at St Richard Gwyn RC High School in Barry, was also pleased with the announcement, he said: "It has come as a bit of a surprise though; all previous information has indicated that we wouldn't see them in person until after Easter," he said.
Laura Doel, from National Association of Head Teachers, said: "We have not had a full return of foundation phase across Wales yet and what we don’t want is to see a is schools having to close again because we have brought in too many learners too quickly.
"The public will not forgive a third lock down.
“The profession stands ready to play its part but the government needs to provide a compelling narrative to reassure parents, carers and communities that their decisions are truly guided by the emerging science.”
Children in Wales aged three to seven started to return to school on February 22.