According to the relevant data of Baidu's experience, it is the most difficult unit of parallelogram in the second book of Mathematics in Grade Two. In the chapter of parallelogram, we first learned the definition of parallelogram, then learned the properties of parallelogram, and then learned the judgment theorem of parallelogram, including five properties and four judgments. It really takes a lot of effort for students to understand all the above definition theorems and use them to solve problems. Therefore, the parallelogram unit in the second book of Mathematics in Grade Two is the most difficult.

Mathematics is a discipline that studies related concepts such as quantity, structure, change, space and information. It is produced by using abstract and logical reasoning to count, calculate, measure and observe the shape and motion of objects. The basic elements of mathematics are: logic and intuition, analysis and reasoning, generality and particularity. Mathematics is applied in many different fields, including science, engineering, medicine and economics.