The educators of America try to create a one school fits all approach. In some cities all the kids from a geographical area will all go to school in the same location. That mix of students will then be taught by the same subset of teachers, all students have similar schedules (daily, monthly, and yearly), and all take tests at the same time. The school is a heterogeneous (not homogeneous) set of students with different skills and abilities.
Some of those students will be on grade level or above, and some will be below. The ones who are not will never receive the extra education they need to catch up, because the teachers are required to teach a certain level of material for a test which will be taken by all of the students in the school at the same time. A single class room is a heterogeneous set of student with varied skills, abilities, and learning styles.
The classrooms and the schools are disorganized in the sense of the abilities and skills of the students.
The goal in school organization should be to create groups of students who have similar learning styles and skill levels. Conceptually, you want to through all of the kids into a big barrel and sort the kids by different factors key teaching factors. The very organization of the school systems in America prevents this from happening. Some are geographically centered and are a sort of organized chaos during the day. Every hour all the kids get up from their seats, run around for five minutes, then go the their next class. There could be more continuity in the teachers, classes, and schedules.
Ideas for organizing schools have been suggested. You could move the teachers instead of the students. That would allow the students to be grouped together based on skills and learning ability. That would work well at the school level, but all of these kids still have the same schedule, which prevents the kids who are behind from receiving extra instruction. The next step would be to have a schools designed for certain tasks.
Many of the schools would be normal schools and would not change. What would change is that the some kids could all be bused to a central location then sent to schools which match there unique needs. Some schools would be schools attending all year round trying get the kids up to grade level, some schools could be schools where the kids have a certain learning style.
After the end of this massive reorganization of a schools system, you will have students organized and sorted according to there abilities, skills, and talents. The students could be tested yearly for placement in the system.
Not all schools would need this micro-organizing of schools, some are just fine as they are. Not all schools systems would need this macro-organizing of the schools system, though the might choose to micro-organize certain schools. Though the large schools systems could reap benefits by organizing their distircs, or organizing in a mid regional area between the district and the school. There could be regional hubs inside of the city which students are centrally bused to, then bused to their specific schools, or it could be the entire city, if it was small enough for travel in a reasonable time.