What did parents, teachers and children do, before Ritalin?
Somehow before Ritalin, means and methods existed, for them to "they learn to control their impulses."
What ADHD? It didn't even have an acronym.
Some kids were just 'busy'. and inventive parents or teachers found ways to keep little Johnny or Janie busy. That requires effort, inventiveness, and attention to what interests a child. Children commonly learned to cope and focus, although not all persons who genuinely have ADHD can.
Recess/play involved vigorous activity, often with minimal supervision, occasional physical conflict, abundant torn out knees in pants and abraded skin by the acre. Helicopter parenting, like the helicopter, was relatively uncommon. Rural (especially farm) kids always had plenty of diverse activities to engage in (lots to do--AKA: chores).
We had a cup of coffee in the morning (another stimulant that promotes focus), got bored with the slower stuff in school, but knew we'd face the track-mounted nun with her WMD (weapon of metacarpal destruction) if we went too far, or the principal with his 'board of education'--a device which was used, and not just a wall ornament. That paled in comparison to the trouble we'd be in when we got home--and our parents would find out--the school would call them, in an era when social services was in relative infancy and not in a hurry to cry "Abuse!" and take children away when they felt the impact of a hand or switch on their bottom. All of that promoted self-discipline. Situations of corporal excess were often dealt with by extended family. Limits were established, and punishment meted in a way that had an impact.
We played outside if the weather permitted (you'd be surprised what that means in different regions, we've had to tell the kids to get off the bicycle and put their hat and gloves on when it was -20 out).
We were also taught by elders we respected, were taught to grant that respect by our elders, and taught those rules of civility applied to everyone, even parents and teachers. But that was a different culture, where the same rules were consistent from home to school, to church, wherever you went, not the sort of confusion that comes from trying to impose common core math on what should have been simple arithmetic.
Much of what we learned was by rote: (...two times two is four, three times two is six....), the right answer was the right answer, and confusion levels were much, much lower.
While there are cases of ADHD (I have met a couple of folks who genuinely had this, and interacting with them in a professional setting was a challenge, but involved realizing what was going on (job went long, his meds ran out, his doctor was 1000 miles away) and steering the conversation back on topic. Not only did that work, but the chap was one of the best Directional Drillers I have ever worked with. But to give children that sort of attention requires that first, the genuine ADHD cases be sorted from disciplinary/behaviour issues, and that there be the ability to deal with both situations. That takes effort and time, which frankly, 'one size fits all' education is not geared to provide. It is far easier to medicate even the borderline cases and even those who just won't behave than deal with them separately and enforce discipline when that is what is needed. (Besides, IIRC, there is extra funding for any 'special needs' kids, by the head, of course).
Again, I know there are people who genuinely have this condition, but question whether it is overdiagnosed as a path of least resistance, especially with school age children. After observing the behaviour of three generations of kids/grandkids/great grandkids, some are just more active and inquisitive than others, and all go through phases where their attention spans are short. Even with that in mind, our children are increasingly routinely stimulated with media and entertainment which promotes a short attention span, a situation which demands instantaneous sensory gratification and not the protracted focus needed to delve in depth into any project.