I am a teacher, although I am one of the thousands of unemployed teachers in California, but I teach high school. I am also a recreational drug user. But school is not recreation to me. I don't go in to the classroom on anything. I can't imagine trying to handle the students if I was was baked.
However, I know when students are baked, or trippin, I can tell if your eyes are pinned or if you have cotton mouth. I can tell when you are talkative and sweaty. I can see you nod. I could have busted a ton of kids because I do all the same substances. On my off hours.
Your teachers may be taking drugs also. But your teachers have to really hide it carefully. You might get suspended. We lose our jobs and our lives crumble if we get caught. But I knew who all my students were and what they were on. I didn't ever say anything except "you need some visine" which i kept in my classroom, or "there is an odor coming from your backpack and the drug dogs around today, so why don't you handle your business" quietly to the student, not to the whole class. I always felt that if you showed up to my class, you deserved for me to give you the lesson that day to the best of my ability considering your altered mindset. You have choice to go to school, or to ditch, every day, and if you showed up for my class, then ok. I accepted my students whatever shape they were in.
I was a good teacher. I can't find a job now and I don't think those teaching jobs are ever coming back. I think my degree and my credential and all my experience is nothing to me anymore and at 51 I have to think about starting out again, working fast food. Life is NEVER so simple as it is when you are a high school student. Adult life can really be a pain in the ass. Adult life is when I personally found out I NEED meds and chems to survive at all.