Crim High: Mathletes was created and published by students at Alonzo A. Crim High School in Atlanta, Georgia. The game is designed to assist younger students to work on mastering their multiplication skills. With a focus on STEM education in schools, there are tons of apps and websites that promise to improve kids' math skills. But it can be hard to find the best tools out there that really help build skills and a love for math. Kids can practice math at all levels with this terrific app. Young kids can develop early skills such as number sense, counting, basic addition, and word problems.