Teachers should treat all students equally, not play favorites.
Tips
history
From the 《梁书·贺琛传》 (Book of Liang, 7th century): originally described differing mourning obligations for one's own family versus adopted-out relatives. Later generalized to any uneven treatment.
usage
Near-antonym of 一视同仁 (yī shì tóng rén, 'treat everyone equally').
