In prison, Kim had a chance to read newly published textbooks about Western culture and science such as Taeseo Shinsa (태서신사; 泰西新史) and Saegye Jiji (세계지지; 世界地誌). He was deeply impressed by the strengths of the new Western science and recognized the importance of education for the Korean people. He started to teach about 100 illiterate fellow prisoners. The Korean newspaper Hwhangsung Shinbo (황성신보; 皇城新報) reported at the time that by his teaching of prisoners Kim Chang Soo changed the Incheon Prison into a school.