`A 51-year-old Malcolm X College instructor who was demonstrating a math problem on her blackboard Tuesday was stabbed in the back by a student who apparently became frustrated with the exercise, authorities said. [..]
The incident occurred around 11 a.m., when a 40-year-old female student in the class repeatedly asked the instructor to explain a math problem and apparently became upset when she couldn’t grasp the material, Chicago Police said.
The student pulled a small steak knife and stabbed the teacher in the left shoulder area, said Monroe District Capt. John Kenny.
Kenny said that before the stabbing the student repeatedly said: “I don’t understand. . . . Explain to me.”’