In classroom teaching, some teachers always try their best not to make mistakes when students answer questions or rehearse. Even for some problems that are slightly difficult and prone to typical mistakes, the teacher has a "clever trick" to let students solve them according to the correct method designed by the teacher, resulting in bad consequences of understanding them as soon as they listen in class and making mistakes as soon as they do it after class. This is actually a reflection that teachers have not fully understood the teaching difficulties and made no breakthrough in teaching. In teaching, teachers can learn from it. Let students expose the wrong solutions, teachers and students analyze the causes of errors together, compare the correct and wrong solutions, and learn from both positive and negative aspects, so that students can truly understand the difficulties and flexibly use new knowledge.