Mathematics knowledge points in Grade One: Method 1: "Do subtraction and want to add" or "want to add and subtract" because 8+7= 15, so 15-8 = 7, 15-7 = 8. The calculation method of "doing subtraction and adding" or "adding and subtracting" seems simple, but it requires students' thinking ability. First, students are required to master addition within 20, so as to quickly apply "doing subtraction to add" or "adding and subtracting".
Method 2: The method of "breaking ten" is 12-5= 10-5+2=7. If students are allowed to think about the calculation method by themselves, it is an unpopular method. This method can only be mastered by students who study under the guidance of teachers. First of all, tell the students that if 3 is not enough and 5 is reduced, don't reduce it first. Let 10 students borrow 1 into one 10-5, and then the number 5 and the remaining 2 are combined into 7. Method 3: The method of leveling ten is14-5 =14-1= 9, and the method of leveling ten is also called continuous subtraction. Its characteristic is that meiosis is divided into the unit of complement meiosis and another number, for example, 5 is divided into 4 and 1, and then into 1.