Interesting they cite Finland and then immediately claim the answer is more schooling. That's not how Finland sees it. In Finland school starts at age 7 as it is considered that before 7 you should be playing, not bored with academics. For those who wish it, a year of "preschool" is available at age 6, the same year the US starts first grade after a year of what is often mandatory Kindergarten, which is now academic and has homework in much of the US, and which follows 1-3 years of preschool and daycare. There is pressure to make preschool academic as well in the US.

Also in Finland, mandatory school lasts 9 years, not 13 years, and you're done at age 16. If you wish, you can at your choice then continue either with college prep or vocational finishing school for three years at no cost with content comparable to a good american community college.

Many systems that do better than the US have kids in school for fewer hours, have less bureaucracy, and cost less to operate than american schools, yet more hours and more spending are always given as the only possible answers to america's supposed school problems, along with dismissing the things that do work in the US, namely homeschooling and private schools which get much better results at a lower cost.