Unit conversion is a difficult point in primary school mathematics teaching, and it is also a headache for many teachers and parents. What can be done to prevent children from making unit conversion mistakes? I think we should calmly and carefully analyze how and why the child is wrong. Maybe we can find a solution to the problem from the analysis. When we help children learn unit conversion, we should first help them remember the progress between units, then tell them whether to convert by division or multiplication, and finally let them work out the results themselves and write down the numbers. If they can't calculate yet, we will tell them the calculation method. From the process of helping children, we just recall the progress between units with our children and tell them the conversion method. In this process, children's learning is always in a passive state, and children don't have much independent thinking, so when they are allowed to finish independently, they will certainly make mistakes.

What's wrong with the child? I summed up that there are several situations in which children make mistakes: First, the speed of advancement between units is wrong, which leads to children's conversion errors; Second, I don't know whether to use multiplication or division, which leads to the wrong method; Thirdly, the propulsion speed is known, and the method is also known, but there are errors in calculation. Why is it so wrong? The reason why children make the first mistake may be because they don't remember the progress between units well, or they confuse the progress between units. I also found in class that some children can't recite the rate of progress between units, and some children confuse the rate of progress, such as making the rate of progress in length units into the rate of progress in area units. The second mistake children make may be that they don't know the conversion method and when to use multiplication and division. The third mistake made by children may be that they are not careful in calculation or are not skilled in calculation methods.

So, how to help children accurately convert units? Based on the above analysis, I summarized the following three aspects:

First: If children make mistakes because of the unskilled admission rate, then we can help children master the admission rate between units skillfully. The so-called proficiency is to blurt out. Some entry rates can only be recited, and some entry rates are not effective, so we must recite them on the basis of understanding. For example, the forward speed of original concepts such as length unit, mass unit and time unit can only be remembered; For some secondary units, such as area units and unit of volume, students can master the calculation method and memorize it on the basis of understanding, which can get twice the result with half the effort. If children are confused about the occupancy rate between units, we must first help them make a distinction. If children confuse the unit of area with the unit of length, or the unit of area with the unit of volume, we can let them distinguish the expression of the unit. The unit of area is generally square, which is the result of multiplication of two units of the same length; Unit of volume is the product of three units of the same length. This method can not only help children distinguish these units, but also help children understand the derivation method of these unit rates and know the origin of these unit rates.

Second: If children make mistakes because of their unskilled methods, then we can sort out the methods with our children, understand and master the method of unit conversion, and then carry out appropriate consolidation exercises to make children master the methods skillfully. I have a class with my children and summed up the four-step algorithm of "look at two things, think twice and calculate four times". Through application, the effect is not bad. At first glance: it is to see clearly which unit conversion the topic belongs to; Two breaks: whether large units are changed to small units or small units are changed to large units; Three thoughts: only consider the admission rate; The fourth calculation: If multiplication or division is required, the rate of progress is from small unit to small unit (decimal point moves to the right), and the rate of progress is divided from small unit to large unit (decimal point moves to the left). Pay attention to the known number divided by the rate of progress, and don't make a mistake; After completing one or two steps, start the conversion.

Third: If the child does not calculate carefully, then we will teach the child how to check, find the mistakes by himself, and help the child develop the habit of checking by himself. If the child's calculation method is wrong, then we must help the child learn how to calculate.

In a word, it is normal for us to find that children make mistakes when helping them with their studies, so we should not worry, be angry or reprimand them for their mistakes. We should calm down and analyze the causes of mistakes with our children, so that children can know where they are wrong, why they are wrong, how to correct them, and how to avoid making mistakes in the future. Only in this way can children learn better and better.