These charges include three counts of sexual activity with a child and one count of sexual activity with a child under 13.
Mr. Foden, 66, from Old Colwyn, Conwy county, was initially arrested in September and had already been charged with three offenses, including sexual activity with a girl aged 13 to 15 and sexual communication with a child.
He has been suspended from his job as a head teacher and is scheduled to appear at Caernarfon Magistrates Court on November 23.