LOS ANGELES — This school doesn't have a problem with students not paying attention.

"They're paying us to come, and our classes are full," says Jeff Jones, chancellor of the Los Angeles branch of Oaksterdam University, where students learn the business of marijuana from seed to ash.

Attitudes are changing as 14 states now have laws allowing some form of legal marijuana use with a doctor's recommendation. And with legalization comes a growing cannabis industry.

In California alone, the medical-marijuana business could be worth as much as $2 billion, says Dale Gieringer, state coordinator for NORML, a marijuana advocacy group. Prices vary widely, but dispensaries have advertised an ounce of dried marijuana for $340 or more.