What sort of stuff do they teach about cannabis in health class that’s so badly wrong? I am not an American so I don’t really know.
I remember in ours while they talked about the dangers of drugs in some disingenuous ways, they also put a lot of emphasis on the dangers of alcohol and nicotine. Specifically I remember them comparing either alcohol or nicotine to cocaine or cannabis or something and saying that the nicotine was more addictive than the illicit substance.
Cannabis isn’t nearly as harmless as people like to think, but that doesn’t mean it’s as harmful as others would have you believe. It’s certainly less physically destructive and somewhat less addictive than something like alcohol which should always be considered a “hard drug”.
Marijuana is addictive though. Maybe not as addictive as some other things, but pretending it’s completely non addictive is disingenuous and misleading. It’s more addictive than say LSD or psilocybin for example.
That isn’t to say it should remain illegal though. Legalisation has positive benefits even for harder, more addictive substances than marijuana. See the history of alcohol prohibition for example, or the disaster that is the war on drugs.