I've been done with school for a hot minute now but here (Netherlands) they started in the last years at elementary school, around age 11. And then some more later in highschool roughly age 14.

Elementary was taught by a cop. Mostly sensible stuff and the risks. Nothing weird but like "weed isn't physically addictive but it can be mentally addictive, also you're probably smoking it and that ain't great." or how xtc is not that dangerous on its own but often there's junk mixed in. They also told us you can get your xtc tested by the government, anonymously. And yeah you actually don't get in trouble believe it or not.

I think it worked because they made it so unexciting that most people I know stay away from anything but weed and even then lots of people try it and never do it again.