>>15196426 (lb)
Barr stepped down in 1974. Epstein hired in 1974.
Could be Barr stepped down in June and Epstein was hired by the new guy over the summer. Probably the Occam's solution, but it is somewhat possible Barr hired him in the spring for the next school year.
Epstein graduated HS at 16, but didn't make it through college. So Epstein graduates HS in 1969 and goes to College, because it was a Draft deferment. Draft wound down late 1971, early 1972, IIRC, when Epstein reached 18, so Epstein may have figured it was safe to quit.
Didn't need a certificate to teach at that time for private schools, but a college degree would be pretty much necessary. Epstein may have 800ed math SATs, or such, and tutored privately to get a math rep good enough to be hired with the right references, especially if it was a late hire, that is, after Barr left. Jury out, still, on Barr, but he could easily have had no connection with the hiring.
Once in the school Epstein would have rubbed elbows with the elites and got his break. Again, nothing to do with Barr.