High school Chinese exams often test translation of classical Chinese.
Tips
usage
古文 and 文言文 (wényánwén) overlap heavily. 文言文 stresses the grammatical register (Classical Chinese grammar, as opposed to 白话 modern vernacular), while 古文 emphasizes the historical/literary dimension, writings from antiquity through Tang-Song prose.
history
The Tang-dynasty 古文运动 (Classical Prose Movement), led by Han Yu and Liu Zongyuan, rejected the ornate parallel prose (骈文) of the Six Dynasties in favor of plainer pre-Qin style, which is why 古文 today often connotes Tang-Song prose specifically.