An educational program was held on 2021 May23rd (Sunday) through online, sponsored by Hiroshima University Astrophysical Science Center, Hiroshima Children’s Museum, and Kagoshima University Amanogawa Galaxy Research Science Center. Several groups of citizens joined the discussion. Professor Kawabata gave a lecture on polarization and polarimetry. Then Professor Sasada, a member of the EHT consortium, gave a talk on Black hole study using astronomical polarimetry.