A boy's high school principal believes easy access to pornography is warping young boys' attitudes and perceptions of the opposite sex.

Principal of Christchurch Boys' High Nic Hill argues that there needs to be more awareness of the issue of boys affected by porn, and what it teaches them.

"The key thing is the false impression of what a relationship is like. The concern is that it's accessible so it's normalising this behaviour when it isn't normal."

Hill doesn't think it's an easy problem to solve.

"It's something as a school we can model and give boys a sense of identity and belonging and strong sense of self worth, but you can't teach morality," he says.

Hill believes parents should be keeping an eye on their teens' online behaviour.