The Assimil method for teaching foreign languages is through the listening of audio cd’s and the reading of an accompanying book, one side native language, one side foreign language. This method is focused on learning whole sentences, for an organic learning of the grammar. It begins with a long passive phase of only reading and listening, and eventually adds active exercises. Most books contain around 100 lessons, with the active phase starting on Lesson 50. The word Assimil comes from assimilation. Several different series are published: With Ease series, which teach basic rules of grammar and a vocabulary of 2000-3000 words; Perfectionnement series, which teaches more advanced idiosyncrasies and idioms of the target language; Business series, which focuses on vocabulary related to international business; Idioms series, which teaches common idioms.