Independent reading doesn't improve children's achievement in reading, at least among children age 11 at the end of elementary school, U.S. researchers say. Nicole Harlaar of the University of Colorado, Boulder, who led the study when she was with Ohio State University, and colleagues at Virginia Polytechnic Institute and State University, Case Western Reserve University and the University of Illinois at Urbana-Champaign, said educators have long emphasized the importance of independent reading for fun or leisure. It was believed getting kids to read more on their own would lead to improved reading scores, Harlaar said The researcher team looked at reading achievement and independent reading in 436 pairs of identical and same-sex nonidentical twins at age 10 and again a year later at 11. Reading achievement was assessed using standard measures of word recognition and reading comprehension, while independent reading was assessed by asking each twin questions about his or her motivation to read. Parents estimated how often their children read for pleasure. The study, published in the journal Child Development, found children's reading achievement at age 10 predicted their independent reading at 11, regardless of how much independent reading they were doing at 10, suggesting that reading achievement influenced later independent reading. However, the reverse was not true -- after accounting for reading achievement at age 10 -- independent reading at 10 didn't predict reading achievement at 11.