CREATE TABLE table_28110 ("Series #" FLOAT, "Season #" FLOAT, "Title" CLOB, "Director" CLOB, "Writer ( s ) " CLOB, "Airdate" CLOB)

Who directed the episodes that aired December 15, 1956?
SELECT "Director" FROM table_28110 WHERE "Airdate" = 'December 15, 1956'
SELECT "Director" FROM "table_28110" WHERE "Airdate" = 'December 15, 1956'