A master worker "speaks bitterness", recounting the hardships of life before the People's Republic.
On the blackboard: 第一课 - 我的卖身契 (First lesson - My deed of indenture).
On the paper the man is crumbling: 卖身 (literally: sell oneself into slavery).
A very similar image from 1972 is BG E37/184, but there the Mao badge and the Little Red Book are absent.