Born in Ipswich, Massachusetts, in 1772, Newman was graduated from Phillips Exeter Academy, which had been founded in 1781 by Samuel Phillips's uncle John. He went from there to Dartmouth, originally intending to become a clergyman, but apparently didn't find a parish willing to accept him. He next tried to secure the mastership of a town school somewhere unspecified, but according to a report in the P.A. archives, his short stature and slightness of build had made the committee doubt “his power to control boys who had conquered the two previous masters. He begged for a trial, and waiting patiently till the tallest & stoutest youth led the riot, he called the master rebel to the middle of the room, [and] gave him a round flogging. ”  Why the committee didn't take him on after that isn't revealed in the documents I have read. In any case, in 1793, he became an instructor at P.A.
In Claude M. Fuess's book Men of Andover, Newman is characterized as “indecisive and fumbling.”  Maybe so, but one good decision he made in 1795, the same year he assumed the P.A. headmastership, was to marry Sarah "Sally" Phillips. At thirty years old, she was Newman’s senior by seven years. The daughter of William Phillips of Boston, she was also a second cousin to Judge Phillips -- not a bad family connection to have in Andover.
His predecessor in the headmastership was Ebenezer Pemberton (1746-1835), who took over after Eliphalet Pearson left for Andover for Harvard in 1786.  Pemberton (1746-1835) stayed for seven years. When he resigned in 1793, he claimed the reason was ill health; however, he shortly started his own academy in nearby Billerica. In Fuess's history of P.A., An Old New England School, he wrote in gossip-column fashion that "everything indicates that he left Andover mainly because he had incurred the displeasure of Judge Phillips, probably because of some love affair which did not satisfy the Phillips family." 
1. Phillips Academy Archives, Head of School records, 1786-1873, Box 1, Folder 3, “Newman, Mark, 1795-1810.”
2. Claude M. Fuess, Men of Andover: Biographical Sketches in Commemoration of the One Hundred and Fiftieth Anniversary of Phillips Academy (New Haven: Yale University Press, 1928), 111.
3. This Ebenezer Pemberton is not to be confused with the one who eulogized George Whitefield. His dates are (1705-1777).
4. Claude M. Fuess, An Old New England School: A History of Phillips Academy Andover (Boston: Houghton Mifflin,1917), 108.