Essentials: Theory of Knowledge (Pearson International Baccalaureate Diploma) for Grade 11& 12 (Pearson International Baccalaureate Essentials) About the Author Dr. Christian Bryan has taught A-level and Diploma Psychology since 1998. He currently works at the American International School of Budapest, where he teaches Psychology and ToK. He is an experienced IB Workshop Leader and EAL curriculum delivery for the Diploma. He is the series editor of the Pearson Baccalaureate Essentials series and co-author of the Pearson Baccalaureate Psychology textbook.