Peer Tutoring Gets a Push
Family dynamics, not biology, are behind the IQ gap between firstborns and their younger siblings, according to a study published by two Norwegian scientists. This study has implications for educators because it proposes that firstborns spend more time engaged in peer tutoring with their younger siblings and that these teaching opportunities help solidify and extend the older siblings' own knowledge. Researchers also determined that second-born men with an older sibling who died in childhood had IQ scores that were nearly as high, on average, as those of firstborn children.
Bjerkedal, T., et al. (2007). Intelligence test scores and birth order among young Norwegian men (conscripts) analyzed within and between families. Intelligence, 35(5), 503-514.