English language learning books for the Introductory and First levels. Introductory (Intro) and First levels of the famous Interchange English language learning series by Jack C. Richards and published by Cambridge University. Two main parts: Student's Book: Workbook: This series is considered one of the most efficient curricula for teaching English to non-native speakers, as it focuses primarily on listening and speaking skills. Comes with a CD. Market price is approximately 400 SAR. For sale for only 150 SAR.