The tower in Pisa leans over in a predictable manner due to a 3-meter foundation set in weak, unstable subsoil, according to authorities. The PISA tests, aka the Program for International Student Assessment, also produce predictable results across 72 countries with 500,000 tested students representing 28 million 15-year-olds.

PISA is not an achievement test. It assesses whether students can problem solve in various subject areas, including reading, math, science and financial literacy. Results from 2015 were reported December 6.

The three highest performing countries do not include the United States. They are China, Estonia and Singapore. Top math scores come from Singapore, Taiwan and Japan. U.S. math scores hit about 38th, above many South American countries, but below most European and Asian nations, even though the U.S. is on the high-end of education spending. But to say that money doesn’t count is not correct. Five of the top scoring countries, including Singapore, invest as much or more than the U.S. on children ages 6 to 15.

Andreas Schleicher oversees the test at the Organization for Economic Cooperation and Development (OECD). According to a New York Times essay, Schleichler’s team runs a game based on OECD research that predicts where countries will fall on their grid. “It’s a parlor game of the high-nerd variety,” says Amanda Ripley, the Times reporter.

To make the game fair, the team assesses results without knowing which countries produce the scores. Once their analysis is completed, they sit around an office in Paris and see how their predictive models match actual results. And presto, they analyze right. Their models can predict 85 percent of variation in scores, up from 30 percent in 2003 when the game was first played.

Their picks are not based primarily on money spent annually on students or poverty rates or immigration. Estonia has high child poverty and Canada has more immigration than the U.S. Yet, both countries score at the top.

Their models, according to the Times, show the elements that cause countries to become “smart.”  First, top scoring countries make the teaching profession prestigious and selective. They direct more resources to their neediest children and they enroll children in high-quality preschools. Schools are managed in a culture of constant improvement. Smart nations apply rigorous, consistent standards across all classrooms.

Schleicher says the U.S. Common Core standards are the only element the U.S. uses “at scale.” Schleicher believes that commitment to Common Core will produce results eventually. “Common Core is going to have a long-term impact. Patience may be the biggest challenge.”

U.S. results have seen “equity improvement” in science, where 33 percent of disadvantaged teenagers scored better than expected, “achieving results in the top quarter of students from similar backgrounds worldwide,” reports the Times. But overall, student scores in science and reading remain flat, and math went down.

American students scored an average 470 out of 1000 on math, with an international average of 490. Singapore scored 564. U.S. students scored an average of 496 in science, meeting the international average. Singapore students scored an average 556.  U.S. 15-year-olds scored 497 in reading, with an international average at 493. Singapore hit 535. Using Olympics medal standards, Singapore brought home the most gold. The U.S. was lapped in every test.