Child Forum chief executive Dr Sarah Alexander said since 2009 their organisation had warned early childhood centres about teachers having personal phones in the classroom.
"It can be dangerous to allow teachers to take photos of children on their own personal devices."
Alexander said their key recommendation was that workplaces should provide devices and images should not be posted on personal pages.
The privacy implications of sharing students' images are real, for example, having a video showing a child's appearance in their school uniform could land in the hands of someone with bad intentions, who would then know where that child goes to school.
And with some teachers boasting over 1000 followers, the images could easily spread.
Privacy commissioner John Edwards also believed teachers should not be posting images of children on personal social media accounts, but didn't think they had to go as far as banning mobile phones from classrooms.
He said there would be value in having an overarching rule on social media as many young teachers had grown up on Instagram and Facebook, and images could expose children to wider audiences than parents would like.
"There are stalkers and all sorts of people that you are broadcasting to [on social media]," Edwards said.
He said although there weren't any rules, they were working on new guidance material on social media etiquette for schools.
It's not just experts that are concerned; one parent spoken to for this story said she would be very upset if images of her child were posted to a teacher's Instagram.
"Even posting on my page I'm careful of what I post and who has access to what I post."
Privacy Foundation secretary and University of Auckland associate law professor Gehan Gunasekara said it was not right for teachers to share posts of students on social media that were gathered in their professional context.
Despite this, he said it would be too difficult to have a umbrella rule as there were always exceptions for example prize givings, but teachers should not post personal information about students.
According to Statistica, 35 percent of Instagram users were aged between 25 and 34 years old, with the largest percentage of Facebook users also falling within the same age group.
Inappropriate social media usage could be just one of the symptoms of having no formal media guidance in the teacher training curriculum.
University of Auckland professor Toni Bruce said the lack in social media direction from training courses meant many teachers weren't using the medium because of uncertainty over what was appropriate.
"From the teachers I've spoken to they would love that kind of guidance [from the ministry].
"Social media literacy is the literacy that people need these days because social media is where we get so much information," Bruce said.
Tawhai school principle Karen Poole said they had a "Publishing Student Information Policy" in place which stated images of students could only appear on school-related media such as the school's official Facebook page.
"I believe that our teachers are not allowed to share images on their personal pages as the consent forms do not include this avenue," Poole said.
She said parents signed blanket consent for official publication during enrolment.
Ministry of Education secretary sector enablement and support Katrina Casey said they expected schools to communicate policies clearly with parents and consult communities when these are updated.
"Each Board of Trustees develops its own school policies that best meet the needs of their students and communities, which could include use of social media during school hours."
She said any parent who was worried about children's access to use or social media usage should speak to their school.
With no set rule on what is and isn't okay for teachers to share, responsibility for checking whether educators can post your child online appears have been thrust on to parents' shoulders.
