Possible Clues:

• Instructs
• Part 5 of today's quote
• Trains
• Fills kids' heads with all sorts of stuff
• Gives instruction, note, and suffers for it
• Instructs Blackbeard on a couple of small points
• Informs about every setback
• Works at a 28 Across
• Works for school in set-up without a head
• Every set-back about it is instructive