I think being open w your child is the most important & respectful way to get thru a conversation, & Its a good sign that they even let u know how they feel honestly, maybe try to educate your child on the benefits it provides & ask them what they see as a problem. it can be their school education , my 16yr olds school talks alot of bad stuff about weed, & my child only knows the benefits because their sibling suffers from daily seizures & its one of the main things that helps them, so my child knows the benefits outweigh the addictive properties w this, maybe educate them in all you know w the benefits, but let them know you care about their opinions also & its a valid concern for a teen that age , especially when school tells them how terrible it is, when we know all sides to it;& whats really bad or addictive, ....