Susan Melnick, the archivist at the Rauh Jewish Archivist, added the annotations (second photo below) pointing out Rabbi Widom and his two sons.  She wrote that the date is 1924 (but doesn’t recall anymore where she got that year from); however, the sons would have been 16 and 20 that year, likely making the older son too old for Hebrew school (let alone that neither looks that old).  I’d date this to 1921 or even earlier.  That the boys are cheder student is a guess by me.  They could also be the High Holiday choir.