* Optical Mark Recognition (OMR) scanner: This machine reads multiple-choice quizzes marked with pencils on special forms. The scanner is the input device in this case.
* Manual grading: A human grader reads and grades the quiz. Their eyes and brain are the input devices, along with potentially a pen or stylus for marking.
* Computer-graded online quizzes: The input device would be the keyboard, mouse, or touchscreen used by the student to answer the quiz questions online. The computer itself then processes the answers as part of the grading process.
So the answer is highly context-dependent.