This book constitutes the refereed proceedings of the 4th International Workshop and Tutorial, FMTea 2021, Held as Part of the 4th World Congress on Formal Methods, FM 2021, as a virtual event in November 2021. The 8 full papers presented together with 2 short papers were carefully reviewed and selected from 12 submissions. The papers are organized in topical sections named: experiences and proposals related with online FM learning and teaching, integrating/embedding FM teaching/thinking within other computer science courses, teaching FM for industry, and innovative learning and teaching methods for FM.