Historical clue formulations

• Guinea pigs, e.g. — 2024-06-22
• G.R.E. sitters, e.g. — 2020-02-21
• Proctors' charges — 2015-09-04
• Proctor's charge — 2014-12-21
• Exam takers — 2012-04-16
• Final participants — 2005-02-26
• High school seniors, often — 2003-10-19