The first grade of primary school, especially the carry addition within 20, is the focus and difficulty of addition and subtraction. As long as you master oral calculations within 20. For example, in the teaching of carry addition within 20, the main teaching method is the method of "rounding to ten", that is, the method of "looking at large numbers, dividing them into decimals, rounding to ten and adding the remainder".

For example, after learning the addition of "9+ several", parents and students arrange the addition questions of 9 plus several in order: 9+2= 1 1, 9+3= 12, 9+4= 13, 9+5 =. Inductive algorithm, "add up to ten". The guide finds out the law of "9 plus several": the first addend is 9, the second addend is getting bigger and bigger, and it is getting bigger and bigger; The total number is less than the second addend 1.

Know the algorithm.

Written calculation training, China's current education system is exam-oriented education, and the standard for testing students is the test report card. Then the students' main tasks are to take exams, answer questions and write with a pen. Writing arithmetic training is the main line of teaching. Consistent with the mathematical calculation method in primary schools, it does not use any physical calculation, and can be used freely horizontally and vertically, even adding and subtracting. Computing with a pen is the golden key to opening an intelligent express train.