A: The commonly used import link types are as follows:

(1) Introduction of warm reasons

The introduction of reviewing old knowledge mainly uses the logical connection between old and new knowledge to find out the intersection of the connection between old and new knowledge, and migrates from reviewing old knowledge to learning new knowledge. This method is often used in the teaching of mathematical concepts and propositions. For example, when we talk about the formula of double angle, we can review the sine and cosine of the sum of two angles first, so as to get the sine and cosine formula of double angle.

(2) instance import

Example lead-in refers to the selection of life cases or students' existing life experiences related to the teaching content, and the introduction of new lessons through the analysis, extension, derivation and summary of the laws from special to general and from concrete to abstract. When the newly taught content is related to and different from the students' life experience, it is usually appropriate to adopt this lead-in method. For example, in the introduction teaching of logarithmic concept, we can start with studying some growth rates around students.

(3) Scenario introduction

Situational lead-in is a kind of lead-in method to stimulate students' imagination or arouse their corresponding emotional experience with the help of multimedia-assisted teaching, so as to stimulate students' interest, induce their thinking and make them turn to new content learning in appreciation or emotional rendering. In mathematics, this introduction method can be used in teaching situations such as geometric graphics related concepts, theorem axioms, mathematical application problems, etc. For example, this import method can be used when explaining the related theorems of parallelogram.

(4) Analogy import

Analogy import means that when two objects have some same or similar properties and some properties of one object are already known, it is inferred that the other object also has the same or similar properties. For example, when learning fractions, you can learn by fractional analogy.