Many people kept their kids "remote", which started a few years ago in response to the pandemic. Many of these kids did not attend any remote classes or do any of their assigned work over that time. Meanwhile this school reopened in-person almost immediately and many families sent their kids back. So you are talking about kids who don't know 1+1=2 or how to read a single word, when the rest of the class is reading intro chapter books and doing double digit math. Socially they are 2 years behind, which is another issue. Perhaps you are a quick learner, but that's really not the case for everyone.

In her school there is 1 math and 1 reading specialist, who are meant to focus on kids like this. Now they need about 5 more of each but the district has routed funding elsewhere like the Olympic quality weightlifting gym for the high school football team (which is used maybe 1hr per day). Better stop, feeling like I'm about to start ranting again...

This is when most kids learn to read. Some kids have basic reading skills before kindergarten, and some learn after 2nd grade. But for most, this is the time when they go from being able to recognize a handful/bunch of words to being able to figure out new words, understand exceptions, and learn about grammar.

There's also a decent amount of conceptual math taught in these grades. I wouldn't say that the concepts are 'hard', but they do take repeated exposure for many kids to grasp them and perform them accurately. You could teach the skills in a week, but only very bright kids would immediately pick up on all of it and not need further practice to be on par with kids who attended K-2. For example, it takes repeated exposure and practice for kids to know that a number ending with 4 and a number ending with 6 will always sum to a number ending in 0. Or to know their multiplication tables.

Does it take three years to learn this stuff? No. But it can't be crammed into a week or even a month.

At 6? The US is behind regardless then. I remember landing in first grade and we all knew how to read already from kindergarten. 1st grade was all about math, learning cursive (which honestly is not that helpful either) and basic life stuff like sending a letter and how the world around us works. My country is shit overall so I’m not bragging, but if my corruption ridden country could make that happen (even if in small pockets) then the us should have the power to make it happen broadly. Only if they listened to the teachers that go in it for the love of it and not the old useless people that manage the system for their profit or stubbornness.

It's not just those grades; I see the same in high school. To a lesser extent, but a lot of the classes that are non-advanced are, here's a 5 question quiz and 15 minutes of content every week, turn it in whenever.

I went to a technical high school with (apparently) one of the toughest curriculums in my city (non US). You know what I found unique? That I didn’t know my curriculum was tough. I just thought that’s the way it was for everyone and went for it. Once we got older and started going out and making friends from other schools is when we realized that no one else was learning calc 1 at 15. The initial success rate of the class was like 95%, few kids had to re take finals around the summer break but no one failed. The admissions were not tough at all to this school, so we weren’t gifted. In fact I failed in college soon after.

What I’m trying to say here is that if we push kids without telling them “this is so hard, you might not be able to do it”, they might just do it. If we pushed the gas a bit further in the content we teach, not only we’ll get people learning more and faster, but also they might get a better sense of accomplishment.