Level One titles are designed to be the first real books a beginner reader will tackle, with very light support from an adult. Each book has a single story with six pages of reading-related puzzles.

Level Two stretch the reader a little more, with more advanced storylines, sentences and vocabulary, plus reading-related puzzles.

Level Three titles have longer stories that encourage children to develop reading stamina. Stories have a strong element of repetition to help the reader gain confidence.

Level Four titles build readers' stamina still further, with 48 pages devoted entirely to the story, more text on each page and more descriptive vocabulary.

Series One titles are for children just starting to read on their own. They use everyday vocabulary, and contain several short stories or one story divided into chapters.

Series Two titles are for children who are reading more confidently. Most titles contain a single story divided into chapters, with varied sentence lengths and more challenging vocabulary.

Series Three titles are for fully confident readers who still need to gain the stamina for standard length books. They use advanced sentence structure and vocabulary, and have more complex plots.