From Overview: Number Worlds is an intensive intervention program that focuses on students who are one or more grade levels behind in elementary mathematics. It provides all the tools teachers need to assess student's abilities, individualize instruction, build foundational skills and concepts, and make learning fun. Number Worlds is the only program that includes a prevention instruction section for students in Grades Pre-K-1. This unique 30-week course of daily instruction improves students' grasp of the world of math so they can move forward with the head start they need.