They should be focusing on reading, writing and arithmetic, but too many teens are drinking and smoking marijuana during school hours according to a new survey.

Joseph Califano and fellow researchers at CASAColumbia in New York just released a survey of 1,000 teenagers.

Nearly every single one of them, 97 percent, said they have classmates who drink alcohol, use drugs or smoke cigarettes, often while school is in session.

"It's likely that the overwhelming proportion of conduct that the kids are talking about is drinking alcohol and smoking pot," Califano says.

Over 40 percent of the surveyed kids said they know a classmate who sells drugs, mostly marijuana.

Fifty-two percent said there's a particular spot on or near campus where students know they can go to get high.

The problem is not limited to public schools. More than half of private school teens said drugs are in their hallways, a 50 percent increase from the year before.

The survey also explored "digital peer pressure", where kids see photos of classmates drinking alcohol or doing drugs on social networking websites.

Three-quarters agreed viewing them encouraged their peers to want to do the same thing.

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