Complex sentence: From 1922 to 1948, the yeshiva was headed by Rabbi Shraga Feivel Mendlowitz, who insisted that he be addressed as Mr. rather than as Rabbi, under whose leadership a yeshiva high school-known as the "Mesivta"-was opened in 1927.
Split into simpler sentences: From 1922 to 1948, the yeshiva was headed by Rabbi Shraga Feivel Mendlowitz, who insisted that he be addressed as Mr rather than as Rabbi. Under Mendlowitz's leadership a yeshiva high school-known as the "Mesivta"-was opened in 1927.