Conversation so far:
Where did Howard Dean grow up?
As a child Howard Dean spent much of his time growing up in East Hampton, New York.
Where did Howard Dean go to school?
Howard Dean attended the Browning School in Manhattan until he was 13.
Where did Howard Dean attend at age 13?
Howard Dean then went to St. George's School, a preparatory school in Middletown, Rhode Island.

Question: What did he attend in 1966?
Self-contained rewrite: What did Howard Dean attend in 1966?