The way mathematics is generally taught, once you fall behind you're basically done. If you get really lost in 5th grade math, you'll spend the next 5-7 years (

The way mathematics is generally taught, once you fall behind you're basically done. If you get really lost in 5th grade math, you'll spend the next 5-7 years (depending on whether your school system requires you to take a math class every year of high school) barely scraping by and getting promoted every year to a new math class while falling ever further behind. Finally, you'll reach the happy point where despite 10-12 of mathematical instruction, you basically don't know any mathematics past basic operations. Much better to adapt to the level of the learner and the speed they can work at - I'd rather have someone genuinely understand all the material that they've nominally learned than get barely passing grades on what looks like more material on paper. Unfortunately, a system of discrete math classes broken up by grade doesn't work any better for slow math learners than for gifted math learners.