On the left top back corner wall the blue-grey characters, 批林批孔专栏 mean, “Billboard for Criticizing Lin Biao and Confucius.”
On the right top corner is an old style loud speaker box with a red five-star on it. This was used for making public announcements.
You can see two book bags in the painting similar to the one here.
War on the Plains is one of the eight Modern Beijing Revolutionary Operas.
Print # 1 in the Appreciation of Modern Art Volume 3
A hardcover notebook with a revolutionary image pasted on the front that says, 干一辈子革命 读一辈子毛主席的书 “Revolution for a lifetime, read books by Chairman Mao for a lifetime.” The inside image is below. The calligraphy reads, 向雷锋同志学习–毛泽东 ”Learn from Comrade Lei Feng–Mao Zedong.”