Historical clue formulations

• Science subj. — 2018-12-15
• H.S. science class — 2011-01-19
• Subj. involving cells — 2010-12-29
• Frog-dissecting class: Abbr. — 2009-04-01
• High school subj. — 2004-01-20
• Junior high subj. — 1997-01-23
• Branch of 39-Down — 1996-07-03
• Sci. course — 1994-10-13