Chat Bus counsellor Averil Pierce, who talks to hundreds of intermediate-age children on a regular basis, said many children had ready access to pornography via their internet-capable phones.
She also questioned the wisdom of providing practical safe-sex information to children as young as 12, who were just entering puberty.
She said there was one school in Dunedin where intermediate-age children were being taught how to put a condom on.
''I find it interesting that, in that school, I also see kids towards the end of the year who are becoming sexually active.''
She said it might be preferable to teach sex education even earlier, before children had any interest in it.
''I don't think we have got it right yet.''
She said schools could put safety programmes on their own computers to protect children but they had no control over pupils' smartphones.
''That gives them free access really easy for whatever - whether that is porn stuff or `how to's or even buying inappropriate stuff.''
She said the ready access to information and more liberal censorship on television meant sexual activity was a lot more accepted in society.
''The more that it becomes acceptable that you don't have to be in a committed relationship to be sexually active ... the more that will just roll on to the younger ones.''
She said the best thing parents could do was educate their children on how to stay safe, and have a good relationship with them so they could talk to them and ''continually'' remind them of the dangers that existed.
