@highfigh, you've mentioned - or at least alluded to - this issue before. Maybe this is the place to start.
School-to-prison pipeline - Wikipedia
From what I have seen and heard on news/shows dealing with the education system, it really looks like the school systems are far less interested in getting the students to connect with the curriculum as a long-term tool than in teaching for the tests and in the Milwaukee system, they're not doing well in the latter, either. I have had interactions with people who couldn't make change without using a calculator or asking for help- that hardly appears to be a case of teaching kids what they need for real life situations.
A lot has changed since 1975- gang activity has grown immensely, making school seem like a dead-end for the short-term because a runner can make a boatload of cash without staying in school. The lack of a functional family unit plays a huge part, too. Addicts having kids who are born with absurd levels of drugs in their system has caused a lot of problems, but that's not new, since mothers smoked and drank while pregnant before that time. As has been said, if they can't find a family at home, they'll find one on the streets.
For those who might think this only applies to the larger cities, they would be wrong- suburban schools have the same problems, just not in the same percentage. Even when I was in high school during the early- '70s, we had the Greasers, who were generally a large PITA, but it's also amazing to see who became what in later years. An oddly large number of classmates who caused a lot of trouble became police officers. Drug use has been common at the high school I attended since the 1960s and that hasn't changed. The surrounding area is really no different, other than in the numbers- Heroin, Meth and Fentanyl are more common, but only Fentanyl is a newcomer- pot & alcohol were the most common, with some using Meth & Heroin while I was there. I don't remember anyone using Coke, but that doesn't mean it wasn't happening. Relatively recently, at least two twenty-somethings OD'd on Heroin in my neighborhood- went to school with both fathers and in another house, I had met the dad when he and his ex lived in the area- his new wife inherited a bunch of money and bought the kids a house about a block away- PD and Fire/Rescue have been called several times for unresponsive adults.
A school system outside of the Milwaukee Metro area has had huge gang problems and this is in an area where they don't have a huge population in specific areas, but it does make up the largest school district in the state. Mostly rural, too.
In the case of some schools, like the one I attended, the parents were affluent and when it came to dealing with the kids, it was more likely that they would hand out money and say "Have a good time" than to ask where they were going, with whom and what they were doing. That was their lives, not mine- when I asked for some things, my parents would say "OK, go and buy one". Boredom is a problem for kids who need something constructive to do and one group started breaking into homes to steal artwork, jewelry and other collectibles. They didn't need the money because their parents were loaded and when I saw the names, I was surprised because they seemed like decent kids.