Reading Explorer is a leveled reading series developed in collaboration between Cengage, the world’s largest educational publisher providing resources for PreK–12, and National Geographic Learning. It is widely used as a designated extracurricular reading material in prestigious institutions, including private schools in the U.S., top schools in China such as the High School Affiliated to Renmin University, and international schools.

The series consists of six levels, starting from Foundation up to Level 5.