Our schools are populated by students who are eager to learn. They have a voracious appetite for ideas and bring passion and energy to the learning process. The ideal student mindset is captured perfectly in the Latin studere, "to be zealous or eager."
Students are also passive beings — sitting quietly, absorbing what is passed on to them, and conveying it back verbatim, never once flagging under the demands made of them. The ability to see eye to eye on this with their teacher is what makes them "good" pupils.
Pupus derives from the Latin for "boy," pupa, for a "girl" Adding the diminutive ending illus(a), resulted in a "little boy" or "little girl." When it came to naming the black circular aperture in the center of the eye, the Romans called it pupillam, because the tiny image reflected in it made you look like — you guessed it — a young child.
In Old English, the pupil of the eye was called the "apple" because it was thought to be a solid spherical body. The teacher's wish to see himself and his values reflected in his students transformed the most zealous or eager into the apple of their teacher's eye.
You see, this also made for bad apples and those at the bottom of the barrel....How do you like them apples?