Achei Temimim is the name of the Lubavitch day schools and yeshivos in several American cities; this page gathers the Rebbe's letters to the Achei Temimim school in Newark, New Jersey, mostly messages for its annual events and appeals (roughly 1960–1970).
Education from the earliest age. The Rebbe taught that authentic Jewish education begins from earliest childhood and is based on Divine guidance, not human convention (IK 9768), and that Jewish survival depends on Torah education from childhood onward (IK 9393).
A personal obligation. Supporting Torah institutions is a personal obligation rooted in the collective commitment made at Sinai (IK 8638); it connects us to eternal values (IK 8407) and ensures true spiritual freedom (IK 8830, 8982). Just as we must ignite our own souls with Torah and mitzvos, we are responsible to kindle others' (IK 9508).
Lessons from the calendar. Chanukah calls for strengthening dedication to authentic Jewish education (IK 7517), and past triumphs over adversity should inspire renewed commitment (IK 10174).
Sources: the Rebbe's letters cited above.