 Welcome. This unit introduces the binary system for the classification of North American vowels, a system which has been adopted by most American phonologists. It differentiates between two sets of vowels, short vowels and long vowels, a distinction where vowel length is primarily determined by the continental environment. This is the initial position used for the North American vowel system, the focus of this unit. In the virtual session, we will first look at the basic implications of this binary vocalic system and will define nuclei and glides. We will then introduce the entire vowel system in detail and will eventually focus on the special case of vowels before R. Use our question sheet as a default guide through the unit if you don't know where to start. The mastery worksheet is a listening task where you have to identify the correct North American vowel that is presented to you acoustically. Well and the practical focuses on the transcription of North American English with special emphasis on the representation of glides in order to deepen your understanding of this probably new transcription system. Could be difficult, but you will manage, won't you?