To implement the principle of saving the lost, we need to do the following: first, we should treat students in two aspects; Second, develop positive factors, fully mobilize students' enthusiasm and overcome negative factors; Third, guide students to evaluate themselves consciously, conduct self-education and promote moral growth.

Carry out the requirements of the principle of long-term goodness and national salvation.

What is good at recovering the lost is that teachers should give full play to students' strengths, do better in excellent aspects, remedy students' shortcomings, and enable students to achieve the goal of all-round development without fatal shortcomings.

Being good at saving losses comes from the Book of Rites: "If you know your heart, you can save losses, while those who teach you are good at saving losses." Among them, goodness is strength, salvation is correction, and loss is negligence and shortcomings.

The principle of saving the lost belongs to the principle of moral education. In addition, there are the principles of guidance, guidance, unity of knowledge and practice, teaching students in accordance with their aptitude, respecting students and combining strict requirements.