You know, I am actually conflicted about this spiraling approach. On the one hand, I don't much care for it personally. On the other hand, it has eased the way to acceleration for a certain type of high ability student. In elementary math, the arithmetic (numbers) topics are pretty intuitive/instinctive and can easily be picked up from day-to-day living but some of the elementary algebra, elementary geometry and elementary statistics topics require some minimal exposure at least to terminology and basic principles. I believe that the end-of-year tests several grades up were easy for DS even in 2nd grade partly due to this spiraling approach. DS had not been tutored or taken through any outside curriculum prior to the testing for his first acceleration in 2nd grade.