watcher

watcher - noun

a close observer; someone who looks at something (such as an exhibition of some kind)

a guard who keeps watch

a person who keeps a devotional vigil by a sick bed or by a dead body

watcher - thesaurus

Scrabble score = 15

"I ran the trial with a small group of students over three weeks before the summer holidays," she says. "I quickly saw the benefits, and signed up."

King's Leadership Academy, Warrington