We are like a curriculum

and all of the lessons are sequenced and follow a logical progression. This is how curriculums generally work and we do recommend you follow the sequence. However, our RATATAZ reader books deliver foundational content in a short 24-page picture book with real science words but not all the extra fluff, so they are not full textbooks and not meant to be. They make look too simple for some older students, but they are just as effective. We made them simple so that the content we are providing is accessible to young readers and we don't shy away from using college-level terms and concepts. If you are going to learn a new language it's best to start with simple books and learning real science is like learning a new language.