Framing the situation as kids being "left behind" feels disingenuous if not outright inflammatory.
Many European systems have been thriving for decades with different school options for different students, based on interest, aptitude, etc. We'd be far better off as a society if we had one classroom for the 8th graders who read at a 1st grade level and one classroom for the 8th graders ready for Infinite Jest. The curriculum and instruction could then be tailored to the needs of each group. Instead, we lump them all together and end up with an outcome where the majority of the students are underperforming their potential.
Many European systems have been thriving for decades with different school options for different students, based on interest, aptitude, etc. We'd be far better off as a society if we had one classroom for the 8th graders who read at a 1st grade level and one classroom for the 8th graders ready for Infinite Jest. The curriculum and instruction could then be tailored to the needs of each group. Instead, we lump them all together and end up with an outcome where the majority of the students are underperforming their potential.