Personally, I feel that this is the highest level application problem in the first grade of primary school, and this concept will continue to appear in the future study of senior three.
In mathematics textbooks, the difficulty is upgraded from counting to azimuth, and from different positions to the reciprocal of positive numbers. And then immediately the cardinal number and ordinal number.
Cardinality represents the total number of numbers. For example, something with 10. When you see one, count 1, and both numbers are 2. 1.2.3.4 ... and so on.
Ordinal numbers indicate the order in which objects appear. The concepts of 1, 2, 3 and 4 ... can be explained by a little joke:
A hungry man walked into the shop and ordered five steamed buns. I was full when I ate the fifth steamed stuffed bun, and I couldn't help feeling: "I knew I was full when I ate the fifth steamed stuffed bun." Why didn't I eat this steamed stuffed bun first? "
At this time, the number 5 can represent the order of 5 and 5.
In fact, the mathematics textbook is only a chapter, but the practical application needs to involve a lot of heavy conceptual knowledge.
At the beginning, there will be a problem of filling in the blanks, judging the total number and finding the X circle in xx line. The requirement is a basic number, which can distinguish left from right.
It is easy to make mistakes if you don't understand the difference between the first few and the last few, and it is easy to ignore if you don't read them carefully.
For example, in the fifth question in the picture, the second animal from the right leaves the team, and () animals?
Is the second, it is easy to make people think that the two of them have left the team, and the result of a word difference is very different.
Next, the question type will be upgraded to:
When counting and arranging positions without the help of pictures, children need to be able to list their own charts and solve problems.
The test is to count numbers and mark the number of interchanges between two concepts.
As shown in the picture, the rabbit is known to be in the ninth place from front to back, and in the third place from back to front. Ask all the numbers.
Draw the position of the rabbit first ▲ Separate the context, and then arrange the remaining numbers.
When you draw a picture, you will find that the ninth place counts forward to 1 bit, and the third last place counts backward to the last place. In fact, the total is the same. As long as you can count, with the numbers in the picture, you can get the final total 1 1.
And if you want to fully grasp the key points of this problem solving, you will go through many tests of different types of questions.
Summary of difficulties in sorting application questions:
The questions summarized today all come from the homework and exercise books assigned by the teacher. )
① Queuing problem-
Count all the people (find out the total)
Where are the numbers (find the ordinal number)
There are still a few in the middle. (Find partial quantity)