In Book 6, Dart Invader Frog, the last book in this self-paced chapter book series, Kate, Marvin, Mrs. Nichols, Tops, and Danger will discover Darty's weakness and they are able to defeat him. Self-paced refers to having vocabulary words at the beginning of each chapter, with questions/answers at the end. A multiple-choice assessment is provided at the end of the book. This series is designed for third and fourth-grade students and for the advanced primary student.