Green’s Dictionary of Slang

(US campus) a very diligent student.

1856		B.H. Hall College Words (rev. edn) 356: poler. One who studies hard; a close student.
1895		J.L. Williams Princeton Stories 41: He studied for high, marks and was called a ‘greasy poler’.
1902		Boston Globe Sun. Mag. 21 Dec. 7–8: To study hard is ‘to pole,’ and consequently one who exhibits unusual zeal in this line is ‘a poler.’.