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 worlds 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.