Each book in the four book series contains 50 short tales, featuring Tobias, a cheerful and worldly-wise character. The stories contain examples of the most common syntactic structures and grammatical morphology in Spanish. Idioms and colloquial expressions are explained at the end of each text. Moreover, the most difficult words and expressions are carefully detailed as well (those which go beyond the level established for each book). After these explanations, the book also includes comprehension activities and topics for discussion. There is a multilingual glossary at the back of the book.