There was a pencil sharpener at the front of the classroom.
puhekieltä That which makes something sharp.
(w), The Shepherd of Salisbury Plain
“Sir,” said the shepherd, “poverty is a great sharpener of the wits. (..)
1872, Chamberss miscellany of instructive & entertaining tracts''
The snuff-box, knife, and chicken-bones were again in requisition, and a pen was successfully formed. The ink, or at least its substitute, was rather more difficult, but necessity is always a sharpener of intellect, and even this was accomplished.