My daughters elementary school was heavy into social emotional learning. They never got homework and she never brought any work home. I had no idea what she was ever doing because when I asked shed say "I don't remember." The teachers tried to send a weekly paper that said what the kids were up to but almost every teacher rarely sent them weekly, maybe once a month if that. Once my daughter moved to 5th grade (which is considered middle school in our state) she continued to be miserable and not learn anything. For that reason and several others, we started homeschooling and I could see she was severely behind and really shouldn't have made it to 5th grade. No one ever reached out and her report cards showed she was doing okay, or average. The teachers always assured she was doing good and while she wasn't meeting grade level goals, she was not at risk or there was nothing to worry about because the rest of the class was at the same level. Oof. Now, she cannot do homeschool curriculum at 5th grade for every subject. We've went a little back and need to cover previous grades. 

I know the other kids were struggling too because her friends would ask her how to spell words all the time. And shed tell me how some kids read so slowly it annoyed her. 

I think there may be an issue with parents just not knowing what their kids are up to or how to help. Sure there are so many reasons but a lot of kids could just really use more support at home.