I brought two fourth-grade children this year and a fifth-grade child two months ago. Similarly, the foundation is very poor, the grades are very low, and the grades of the two children in the fourth grade come up quickly. Because the fourth grade is relatively few, it is easier to make up, while the fifth grade is not only rich in content, but also relatively difficult. The previous knowledge points are not understood, which directly affects the later learning. The fifth-grade child I'm taking now doesn't understand the fifth-grade knowledge and can't find the least common multiple of two numbers, which leads to his failure to score. He can't add or subtract grades in the fifth grade, but he does one occasionally. He didn't see the common factor between numerator and denominator, and he didn't know the divisor, so he didn't do it right, so he only got 19 in the first unit math exam. Before I could understand the addition and subtraction of fractions, the cube came again. What side length, surface area and volume are all messed up. I can only do the problem again and again, explain it again and again, and finally understand it. I learned fractional multiplication again, and then I confused fractional addition and subtraction. Do the problem of fractional multiplication, get rid of the score, practice almost the same, add and subtract fractions, and forget the score. In short, it is really difficult to learn the front and forget the back, and learn the back and forget the front.