By Justin Parkinson
BBC News education reporter
What is the best way to stop children turning to drugs?
Experts warn against drugs scare stories
That is the question confronting schools across the UK.
Head teachers - armed with only the powers of persuasion and punishment - are left to fight an illegal industry worth an estimated £6.6bn a year.
Drug dealers, with so much money at stake, are experts in marketing their wares.
Peer group pressure, manipulated for commercial gain, is a powerful motivator.
'No easy cure'
The 1980s slogan "Just say no" simply will not do for increasingly media-aware teenagers.
Jenny McWhirter, head of education at the charity Drugscope, wants a subtler effort.
She said: "What we've learned over the years is that people are quite complex.
"We need different approaches for different people, because they have different needs and motivations.
"There is no golden bullet to solve the problem and it's not like there's one inoculation that can save people from the risk. We have to keep the effort going."
Ms McWhirter is keen to point out that not all figures on drugs are bad news.
Since 1997, young people's use has remained fairly constant, with a slight decline in the proportion of 11 to 15-year-olds taking cannabis.
But, during that time, the number of times a teenager is likely to be offered drugs has increased.
Somewhere along the line, a message seems to be getting through.
Ms McWhirter said: "Most young people do not use drugs, but we have to target those who do.
"Some groups, such as children of drug-users and the socially disadvantaged, are particularly at risk and we have to address that.
"For some risk-averse kids, the shock-horror approach, where you outline the dangers, works - but not for all kids.
"A lot of the time, young people take drugs because they do not feel they can connect with adults, or the community.
"Some heads are doing great work with football teams and after-school clubs, to try to give children that sense of belonging."
'Place of safety'
Since 2003, every secondary school in England has had to have a drugs policy in place.
But in July the education watchdog Ofsted reported a "mixed picture", with "too little focus on the social implications of drug-taking".
Kent County Council is looking at introducing random testing in classrooms.
It has tested the policy at The Abbey School in Faversham and is extending the pilot scheme.
According to the council, pupils feel they have "a strengthened argument to resist peer pressure and feel themselves to be in a place of safety".
Council leader Paul Carter said: "Peer pressure on young people today is immense.
"Simply saying no is no longer an option; the very real threat of random testing might just give them the support they need to refuse drugs.
"This is not a case of catching children out but empowering them to make the right choices."
However, Ms McWhirter feels random testing will break the relationship of trust between pupils and teachers.
She also thinks the approach, which is unlikely to happen again after young people leave school, does little to reduce drug use or encourage personal responsibility.
Ms McWhirter said: "The problem with much of teaching about these issues is that the teachers are amateurs. They did not train for it at college but they are expected to do the job.
"Also, the media, with the shock message of 'cocaine in the playground', make it look as if a bad situation is the norm - and it isn't.
"We need to tailor what we teach kids to their needs, to explain the real scope of the problem."