Mr Ortiz Called on Jessica to Come to the Board

Mr. Ortiz called on Jessica to come to the board and diagram her answer to a question. Jessica could feel all of her classmates staring at her as she made her way to the front of the class. As Jessica began to write the problem on the board, she realized that she was not sure this answer was correct. She could hear giggles coming from some of her classmates, she was heavily perspiring, and her stomach began to hurt. She finally just dropped the chalk and headed back to her desk. She could hear her classmates whispering and giggling all around her. Now, Jessica does not like attending Mr. Ortiz's class; she always feels nauseous, especially on Fridays, which is when he calls on students to go to the board. Identify the US, UR, CS, and CR.