I'm sorry the comment describing how SFUSD had eliminated algebra from middle school [0] has been deleted. Waiting until junior year to split up a class based on math aptitude is probably good for those in the middle, but it's certainly bad for those with higher or lower than average aptitude. As I recall, my pre-algebra and algebra I courses were attended by two classes: 7-8 and 8-9 grades respectively. After that there was no requirement that you take a particular course in a particular year, just that you had passed the prerequisites. This seemed to work very well, since everyone was ready for the material.

[0] https://priceonomics.com/why-did-san-francisco-schools-stop-...