repeater
n.a person who repeats something they have heard or a machine that sends a signal again. In old math, it was a student who could repeat a lesson perfectly.
n.a person who repeats a lesson or a signal; a device that retransmits a signal to extend its range. In historical educational contexts, refers to a student who has mastered a lesson to the point of perfect recall.
“The radio repeater sends the signal to the mountain top.”
“The teacher asked the repeater to lead the class in reciting the multiplication tables.”
“In the early days of wireless communication, a repeater was essential for maintaining a clear signal over long distances where the original transmission would otherwise be lost.”
From repeat + -er.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.