What do Education and Economic Growth Have in Common?

Studies have proven that a good quality education has a strong positive correlation with Economic Growth. A study, Education and Economic Growth, Its not Just Going to School, but Learning Something There That Matters by Eric Hanusheck, Dean Jamison, Eliot Jamison, and Ludger Woessmann, published in Education Next examines the relationship not only between attendance and actual learning, but on the strong relationship between education and economic growth. The study notes that other studies have only looked at the relationship between student attainment and economic growth and hum and human capital. The problem with only examining student attainment falls in the fact that those numbers only quantify the number of years a student was in school, not how much they learned.
While the study did find that student attainment did have a positive correlation with economic growth, more actual learning has a greater effect. As other economists in the past found, the study found that if the average number of years of schooling was higher, the economy grew at a higher rate in the following decades. Studying 50 countries, each additional average year of schooling increased the average 40 year growth rate in the GDP by .37 percentage points. When they examined cognitive skills, which were measured my the performance in math and science tests, the impact is much larger; countries with higher test scores experienced much larger growth rates.
There is obviously a strong correlation between growth and education, but then were does money spent on education come into play? Over the years, more and more money has been poured into education yet these attempts have failed to yield actual improvements. In order to help economic growth (let alone, our children) we need to focus on education reform tactics that truly work.