- Interchange Third Edition is a 4-level series for adult and young adult learners of English from the beginning to the high-intermediate level. The Workbook has six-page units that follow the same sequence as the Student"s Book, recycling and reviewing language from previous units. Workbook B contains units 9-16 and provides additional practice in grammar, vocabulary, reading, and writing. The Workbook can be appropriate for in-class work or assigned as homework.