This is from the article, Singapore Math: Intensive Teacher Trainings, in the Dyslexia Tutor: News Resources by Adrienne Edwards about Singapore Maths.
When the US Department of Education commissioned a study in 2005 to find out why Singapore, a country with a population half the size of New York City, ALWAYS scores No. 1 in a widely accepted comparison of global math skills, it concluded, “Singapore’s textbooks build deep understanding of mathematical concepts through multi-step problems and concrete illustrations that demonstrate how abstract mathematical concepts are used to solve problems from different perspectives.”Find Singapore here.