Teenagers are drinking at increasingly younger ages and bringing more problems into school on Mondays after booze-fuelled weekend parties, according to the head of one of Perth's most prestigious girls' colleges.
Presbyterian Ladies' College principal Beth Blackwood said society should be concerned about the increasing prevalence of under-age drinking by students as young as 13 and its effect on adolescent brains.
She recently called PLC Year 9 parents together to urge them to be less trusting of their daughters and to say "no" more often after seeing more problems this year with a partying and drinking culture among that age group.
"We need to be proactive as parents, as educators, in saying 'no' to alcohol for adolescents, rather than that attitude of 'well, we all did it when we were young'," she said.
"We need to recognise there are different dynamics at play and we are privy to more information now than we were even 10 years ago about the harmful effects of alcohol on an adolescent brain."
Ms Blackwood said under-age drinking was starting at a younger age than in the past.
"The pattern some years ago was more likely to raise its head in Year 10," Ms Blackwood said.
"We now see it in Year 9 and as early as Year 8."
Students were regularly reporting to counsellors their embarrassment about rumours or pictures posted on social media after getting drunk at weekend parties.
She was also concerned by changing patterns in teenage drinking behaviour, with teens more likely to drink before going out.
Vodka had become the drink of choice because it was harder to detect and provided a cheap way to get drunk quickly.
Ms Blackwood and other school principals had backed a petition calling on the State Government to introduce secondary supply laws to ban adults from giving alcohol to teenagers without their parents' consent.
Churchlands Senior High School principal Neil Hunt said there was a big party atmosphere among students from western suburbs schools.
"The parents know they are drinking and in fact in some cases put on extra champers for the kids," he said.
Boys' school heads Alec O'Connell, from Scotch College, and David Gee, from Wesley College, said under-age drinking was a societal issue.