Think marijuana is harmless?
But now, research from Canada lets us know more about how weed can change your attitude towards school.
The study, which followed about 26,500 students from Ontario and Alberta, found that those who started using marijuana at least once a month were 4 times as likely to skip class, two-to-four times less likely to do their homework and half as likely to get high grades compared to when they started smoking.
And it looks like the more they smoked, the less they cared about school.
When students started smoking marijuana every day, they were less likely to want to go to college, according to the study.
The brain does not stop developing until you reach your early twenties. When you start smoking weed in your teens, the damage you do to your brain could last a lifetime.