Reverse thinking is equivalent to reverse thinking in the way of thinking, that is, starting from the result of things, the conditions needed for reverse thinking to get the result. In mathematics learning, there are many concrete problems that primary school students can't solve or are difficult to solve with positive thinking, but it is easy to use reverse thinking.

Second, the role of reverse thinking

Ji, a famous math teacher in primary school, once taught a section on "backward push strategy", which created a very interesting situation: there are five goldfish in the picture, and there are a bunch of intertwined and complicated fishing lines above the goldfish, and only one fishing line hooks one of them. He asked the children to find the fishing line that hooked the goldfish. What's the number of the fishing line? Children who are good at positive thinking can find the answers one by one from the fishing line, but it takes a long time; Children who try to use reverse thinking, starting with the fishing line hooked on the fish mouth, look back for the source of the fishing line and soon find the answer. The creation of this situation suddenly attracted children and made them deeply realize the advantages and benefits of reverse thinking.

After learning the content of converting units by decimal point position, there is an exercise in the workbook: fill in the appropriate unit name in the following brackets: 360 () = 0.36 (? ), this question has a high error rate. The reason is that children don't know how to think about such topics. They often use positive thinking. Fill in the unit name in the first bracket, and then think according to the unit name. Which company name can be filled in the brackets to match this number? Since this method can also solve this problem, the thinking process is chaotic, purposeless, time-consuming and error-prone.

But on the other hand, if you use reverse thinking, first think about how to operate 360 to get 0.36? Known: 360÷ 1000=0.36. According to the division, 360 to 0.36 is the conversion from low-level units to high-level units, and then according to the number divided by 1000, it can be inferred that the progress rate between these two units is 1000, and thus the progress rate is 1000.

Third, the classic topic of using reverse thinking

In the process of primary school mathematics learning, there are still many typical problems that need to be solved by reverse strategies. For example, the classic topic Li Bai drinks: Li Bai walks in the street, buys a pot of wine, doubles it when he meets a shop, drinks a bucket when he sees flowers, and drinks all the wine in the pot three times. May I ask how much wine is in this pot? Another example is the classic topic in modern times: a road, with a total length of 5 kilometers for the first time, 2 kilometers for the second time, and 1 kilometer for the third time. At this point, there are still 5 kilometers. How long is this road? Such problems, even if primary school students learn equations, the equations listed by positive thinking can't be solved, but they can be easily solved by reverse thinking.

Mathematics learning not only needs positive thinking to straighten out ideas, but also needs reverse thinking to assist difficult problems. Regular reverse thinking training can make students' thinking more and more open and flexible.