Historical clue formulations

• Elementary education ... or feature of the last words punned upon in 17-, 29-, 49- and 66-Across — 2016-01-13
• Fundamental group — 2006-12-16
• Education fundamentals — 2006-11-01
• Classic school group — 2003-04-19
• Schoolmarm's impartation — 1999-07-09