As I study math education deeply these days, I find myself frustrated with the grade level configuration of school--a configuration that expects learners to achieve at the same rate for all subjects just because they are the same age.
Learning doesn't work this way. Students follow their own developmental/environmental paths of learning.
For example some children who have lots of books read to them and a predisposition for reading early,may come to kindergarten fully ready to read while other students who perhaps struggle with words on a page or who have little experience with books or story may need a few years of study to begin reading.
The same is true for math, students progress differently.
Rather than embracing the different ways that children progress with regard to academic skills and interests, we label them as below, at-grade, or advanced as we compare them to their age mates.
Instead we could embrace the notion that every child is on a learning course, and we could work to create and employ programs to move every child ahead with regard to core academic skills of reading, writing, and math as well as interdisciplinary study in areas of interest, the arts, humanities, and STEAM (science, technology, engineering, arts, and math).
There are schools that embrace a developmental structure that allows students to grow at their rate rather than moving them ahead just because of age even if they haven't mastered the foundation skills needed to move ahead.
This is also true for testing. I think it's crazy that we test students by grade rather than be performance levels. If we're going to test, allow students to start at an entry level and test up to where their knowledge, skill, and concept levels off--a place where they can begin to learn more. Then they could test again to see what progress they've made.
Let's take a close look at the students in our schools. What do they need to succeed? Then let's match educators, programming, structure, schedules, and resources to meet those needs in the ways that research point to for greatest happiness, success, and progress. Most schools have lots of room for growth in this regard.