Teach with confidence, using the world's favorite English course. Interchange is a four-level, American English course that has been used by over 50 million students worldwide. This Level 1B Workbook provides six pages of additional practice for each unit in the second half of the Student's Book (units 9-16). The workbook helps recycle and review language by providing additional practice in grammar, vocabulary, reading, and writing. It is appropriate for in-class work or can be assigned as homework.