The data actually show if you don't master the 5th and 6th grade material you can't learn what's taught in the 7th grade and high school.
The school moved kids ahead even though they never learned the earlier grade. Many school are now graduating graduates that are illiterate and innumerate.
Heck, they've been doing that for a long time now. Because math, English and reading and writing are racist, dontcha' know? So now they just graduate illiterates so the teachers can feel like they're doing a good job and get more big govt money. The money's all that's important to them anyway.