If they get more achieving grade level, isn't that what we want?

Not necessarily if it means there will be a barbell curve, and we get equal or more students doing even worse. Teachers will quickly bucket kids into 3-4 groups:

1. Doing fine, no need to even pay attention to these kids. Now your top performers don't grow as much. 2. On the edge - where most attention will go 3. Meh - maybe a small percentage jump into category 2, where they will be cared about 4. Let them rot - most of the kids at the bottom will just be let to rot

Do you really think that they aren't already letting the bottom quartile rot? It's hard to see how things could be worse.

In my career in public schools, I never noticed any efforts by the teachers to grow the top quartile. Or anyone else, for that matter. I attended 4 public schools in different locales. I was pretty much ignored by all the teachers.

I remember first grade. The teacher would set us up in a circle, each student reading one sentence. I found this very dull, and so read the rest of the book while the other students would grind out the sentences. The teacher then asked what the students guessed the next chapter was about. I of course piped up and dumped a summary of the rest of the book. The teacher was not amused, and curtly told me I was not allowed to read ahead of the class.

Nurtured, my adze.

Things have probably gotten worse since. For example, Seattle got rid of all their gifted tracks.

I went to a public school where the entire motive energy of the staff was applied to the top quartile. Being in that quartile, it was really great. Every class was leveled and the best teachers taught Honors classes. I cannot describe how refreshing it was to be in a class where those 2 or 3 disruptive kids had just... disappeared.

This is also fundamentally a better way to run a country. It really doesn't matter whether the bottom student in the school does or doesn't learn how to add two three-digit numbers by the time he graduates high school. But the top student learning more advanced topics could actually matter.