An online campaign is building in resistance to the Tasmanian Government's plans to lower the school starting age from the year children turn five to three-and-a-half.

The changes to the Education Act will be debated by Parliament in a few months and implemented in 2020.

There are claims the plan has not been well thought out and academic evidence is being ignored but the Government said the opposite was true.

Education Minister Jeremy Rockliff said the change would combat high levels of disadvantage and low levels of educational attainment.

The State Government believes starting children earlier benefits the disadvantaged. ( ABC News: Nadia Daly )

But this was refuted by Jannette Armstrong, a union representative for childcare workers and the creator of a social media page campaigning against the reforms.

Ms Armstrong believes increasing support for disadvantaged families would be more beneficial.

"They'll be potentially labelled earlier as troublesome or failing and earlier they get this sense of you know what, school's not for me and that will stay with them forever," she said.

But Tasmania's Children's Commissioner Mark Morrissey said the change could help disadvantaged children.

"The reality is that Tasmania has far too many children and young people not receiving rich play-based developmental opportunities that will be critical to them living successful lives," he said.

Mr Rockliff said overseas and national research showed quality early learning was key to improving educational outcomes.

The academic evidence

Studies show early introduction of formal lessons does not improve literacy rates. ( Sophie, file photo: www.sxc.hu )

A New Zealand study between 2007 and 2012 found introducing formal literacy learning earlier does not improve children's reading development in the long run and instead, may be damaging.

Research in the United Kingdom and United States has shown children who attend primary schools with a play-based curriculum perform better than schools focusing on formal learning.

Other international studies have linked the early introduction of structured learning with increases in mental health problems.

One of the leading academics in the field, David Whitebread from the University of Cambridge, said any formal learning under the age of six was likely to be counterproductive, particularly for disadvantaged kids.

"All the evidence we have suggests what early schooling does is actually increase the divide," he said.

Marie Hammer from Monash University in Melbourne said it depended on the quality of the curriculum, and added it must be play-based and that teachers must be trained in early education.

"Pressure on children in Asian schools where they have to perform at a very early age has led to quite an increase in suicide rates and self-harm," she said.

So is the curriculum play-based and if not will it be changed?

The Education Minister said there were no plans for the Government to change the curriculum.

Kindergarten student 'cooking' in the outdoor kitchen. ( ABC News: Angela Ross )

"Kindergarten is play-based and to a certain extent as well prep is play-based," he said.

But Ms Armstrong disagreed and said preparatory classes were academically focused and she believed pressure would only increase on young children.

"Recently with the federal budget that came out in May there was talk around implementing more NAPLAN-style testing for children in that prep cohort so it's pretty scary," Ms Armstrong said.

Concerns about class sizes, teacher training and ratios

Parents are concerned about class sizes and teacher support for younger students. ( ABC News: Angela Ross )

Parents have questioned if there will be a cap on class sizes for younger children, whether preparatory teachers will have aides because their students will be younger and if teachers will be retrained.

The Education Minister would not commit to a cap on class sizes but he said extra support would be provided to teachers and infrastructure would be upgraded.

"We have over three-and-a-half years to ensure that we have the resources in place, both human resource and of course capital requirements to ensure this is a smooth transition," Mr Rockliff said.

Toileting concerns among parents

Families are concerned about youngsters who may not be fully toilet trained. ( Flickr: Laura Smith )

Tillie Butterworth, who is expecting her fourth child later this year, is among a number of parents concerned about the change.

"One of my children was barely toilet trained at three-and-a-half he was not at all ready, the other one possibly would have been ready but I think at three-and-a-half years old they need care more than they need schooling," Ms Butterworth said.

Ms Armstrong said the education department has told her nappy change tables would be placed in kindergarten classrooms.

"That would really contradict the current policies in the education department where teachers and teachers aides aren't really allowed to touch the children," she said.

"I don't know how these children are going to be assisted to have their nappies changed or be assisted if they're still learning the toileting process and how children at this stage when they're upset and they just need a cuddle are not going to be able to get that nurturing."

Mr Rockliff called for calm.

"I understand the questions that people have and we will answer those questions in terms of any changes and how that may impact," he said.