Singapore Primary Mathematics is a secular math program that covers 1st through 6th grade levels. Conceptual understanding, mental math, and word problems are an important part of the curriculum. Read more about it at ChristianBook.com.
The Singapore Discovering Mathematics/ Dimensions Math is designed for grades 7-11. It covers pre-algebra, geometry, algebra, as well as some trigonometry and advanced math concepts in an integrated way. Read more about it at the Singapore website.