Some teach by writing books, others deliver lectures, still others regularly issue public letters, essays and commentary. The Lubavitcher Rebbe, widely regarded as one of the most influential teachers of our generation, did all of the above; but his primary medium of teaching was the farbrengen.
A brief history of the Six Day War and the Rebbe's call for all Jewish men, particularly soldiers in the IDF to don Tefillin as a special merit for added security