David Bohlke has over 30 years of experience as a teacher, teacher trainer, program director, editor, and materials writer. He has lived and worked in Japan, Korea, Singapore, Australia, Saudi Arabia, and Morocco, and has conducted multiple teacher-training workshops in Asia, the Middle East, Latin America, Africa, and the Pacific. As an editor he has worked on some of the world’s best-selling ELT courses for teens and adults. For National Geographic Learning he has authored the series Time Zones, Keynote, and Reading Explorer. David holds an M.A. in Applied Linguistics/TESOL. Nancy Douglas is a teacher, materials writer, and editor who has been in ELT for over twenty years. She has extensive experience working with students from around the world and has co-authored several courses, including the best-selling series World Link and Reading Explorer. She has also edited print and Web-based materials for English language learners as well as professional development courses for teachers.