In Part 1 of the article, empirical findings are listed that are consistent with a heterocyst hypothesis but render other hypotheses either implausible or very difficult to test. In Part 2, a formal model of the process of heterocyst is presented. The goal of the modeling is to develop a quantitatively rigorous method for estimating the potential contribution of heterocyst in the Flynn effect, as well as trends observed in other heritable traits and conditions.
Numerous studies of the age-grade progress of school children have afforded convincing evidence of the magnitude and seriousness of the retardation problem. Statistics collected in hundreds of cities in the United States show that between a third and a half of the school children fail to progress through the grades at the expected rate; that from 10 to 15 per cent are retarded two years or more; and that from 5 to 8 per cent are retarded at least three years. More than 10 per cent of the $400,000,000 annually expended in the United States for school instruction is devoted to re-teaching children what they have already been taught but have failed to learn.
The first efforts at reform which resulted from these findings were based on the supposition that the evils which had been discovered could be remedied by the individualizing of instruction ...Show more