The way it works now is that 20% of the bottom students eat up 80% of a teacher’s time and resources. I’m not saying it’s a bad thing depending on what your goals are. What I am saying is that you can’t have everything. You have to choose. This system this comment describes and the system your comment below describes cannot coexist.
That just means that we need to move the bottom 20% of students into their own classes where they can get the extra attention they need. That means they can get a high quality education and so can everyone else. You do not have to choose. You can have both.