Conversation so far:
What is important about L. Frank Baum's South Dakota years?
L. Frank Baum's description of Kansas in The Wonderful Wizard of Oz is based on his experiences in drought-ridden South Dakota
Who were L. Frank Baum's parents?
L. Frank Baum was the seventh of nine children of Cynthia Ann (née Stanton) and Benjamin Ward Baum.
Did L. Frank Baum have siblings?
L. Frank Baum was the seventh of nine children.
Where did L. Frank Baum go to school?
L. Frank Baum was tutored at home with his siblings. From the age of 12, he spent two miserable years at Peekskill Military Academy.

Question: where did he go after that?
Self-contained rewrite: where did L. Frank Baum go after that Peekskill Military Academy?