This article analyzes the magnitude of individual differences in academic achievement and their growth over the first 9 years of schooling. The author anchors the widening-gap phenomenon on the theoretical recognition of large individual differences in learning pace, which logically leads over time to an increasing gap in knowledge and skills between the fastest and slowest learners. The achievement data used as evidence were borrowed from the developmental standard score (SS) norms of the Iowa Tests of Basic Skills (ITBS: Hoover, Dunbar, & Frisbie, 2001). These norms reveal, among other things, that within most grade levels the range between the lowest and highest achievers exceeds the 8-year gap in knowledge between average 1st- and 9th-grade students. Moreover, the achievement gap widens by about 145% between grades 1 and 9. Parallel evidence suggests that standardized achievement test data probably underestimate the true differences. Because it ensues from stable individual differences in learning aptitude, educators should not perceive that widening achievement gap as a failure of the educational system, but should recognize it instead as a proof that all learners are given the opportunity to progress at their own learning pace.
PUTTING THE RESEARCH TO USE:
This demonstration of a huge gap in academic achievement between the fastest and slowest learners constitutes a powerful argument in favor of curriculum differentiation, ability grouping, and academic acceleration. It is hoped that readers will find the results impressive enough to discuss them, using Figures 1 and 2, with friends and colleagues. Readers are invited to target school professionals, administrators, and school board members as those most likely to benefit from this information. They could highlight with these educators the fact that the gap in academic knowledge within most grade levels is huge, even exceeding the knowledge span between average 1st- and 9th-grade students. Secondly, they could introduce the talent search data, whose results suggest an even larger span than what the ITBS data reveal. Thirdly, they should stress that the growth of the achievement gap over time – the fan spread effect – is a logical outcome when all students are given the opportunity to progress at their own learning pace. Fourthly, they should point out that these results constitute a powerful argument in favor of curriculum differentiation, ability grouping, and academic acceleration. Finally, it is hoped that many school principals will make the contents of this article an object of discussion at a faculty meeting.