An online grading system is a system that utilizes internet technology and electronic devices for the marking and scoring of examination papers. Its working principle generally involves the following steps:

1. Student Answer Sheet Upload: After students complete their exams, they upload their answer sheets to the system server via the online grading system. They can upload the electronic document directly or convert the paper answer sheets into electronic documents through methods such as taking photos or scanning before uploading.

2. Batch Exam Import: System administrators import exam templates and standard answers through the system interface. Exam templates include information such as question layout, type, and score distribution for each question. Standard answers include the correct answers for each question and corresponding scoring criteria.

3. Answer Recognition and Analysis: The system employs Optical Character Recognition (OCR) or image recognition technologies to automatically identify and analyze student answers. For multiple-choice or fill-in-the-blank questions, the system can automatically determine scores by comparing student answers to the standard answers. For subjective questions, the system can provide support for teacher grading, such as offering scoring references and displaying standard answers.

4. Auto-grading and Manual Intervention: The system automatically grades student answers based on pre-set grading criteria, evaluating the match between standard answers and student responses, the accuracy of choices, and the completeness of fill-in-the-blank questions. Additionally, the system allows teachers to manually intervene, grading certain questions by hand or modifying auto-graded results.

5. Data Storage and Reporting Generation: The system stores the grading results and student answer sheet data in the database, generating relevant reports and statistical information. For instance, the system can produce student grade reports, scoring statistics, and class performance analyses, enabling teachers and schools to conduct data analysis and evaluation.