From your own link it doesn't seem to enter into it much if at all. Not only has it had the least effect on school subjects but some of the increase has been shown to be because of improved test taking skills rather than actual intelligence improvements.

>There is debate about whether the rise in IQ scores also corresponds to a rise in general intelligence, or only a rise in special skills related to taking IQ tests. Because children attend school longer now and have become much more familiar with the testing of school-related material, one might expect the greatest gains to occur on such school content-related tests as vocabulary, arithmetic or general information. Just the opposite is the case: abilities such as these have experienced relatively small gains and even occasional decreases over the years.

>Researchers have shown that the IQ gains described by the Flynn effect are due in part to increasing intelligence, and in part to increases in test-specific skills.