0 1 combination to identify numbers and develop a sense of numbers.
The carding of "knowing numbers within 100" mainly includes further understanding of numbers, counting units, the composition of numbers, improving the reading and writing ability of numbers, feeling the size of numbers, and thus developing a preliminary sense of numbers. The emphasis is on the meaning and reading and writing methods of numbers within 100, and the difficulty is to describe the size relationship of numbers with "more", "less", "more" and "less".
1 Create a digital concept
It is necessary for children to establish the concept of number, because it is the premise and foundation for understanding the meaning of number, reading and writing correctly, sorting out the order and size of number, and clarifying the composition of number, which can make them form a corresponding sense of number and have an important influence on understanding larger numbers in the future.
Remember that "from the right, the first digit is a unit, the second digit is a tenth, and the third digit is a hundredth", and make it clear that the number on the unit represents several ones, the number on the tenth digit represents several tens, and the number on the hundredth digit represents hundreds. In this way, to understand the composition of numbers, we can put the numbers in the numbers to analyze, which is naturally much simpler.
When reading, you should read it dozens of times in ten places and several times in one place; When writing numbers, tens are written in ten places, and some ones are written in one place.
When the proportion is large, the one with more digits is larger. If the number of digits is the same, both are two digits, then it is greater than ten digits first, and the number of the first ten digits is even greater; If ten places are the same, then compare them.
2 Perception of "full 10 forward 1"
The basic counting method of "full 10 decimal 1" is the key to digital recognition. When reviewing, let the children realize that all the sticks with a total of 65,438+00 should be tied into a bundle, that is, 65,438+00 is 65 and 438+0 is 10; 1 bundle 1 bundle number. If the quantity exceeds 10 bundle, it will be bundled into a large bundle, that is, 10 is 100.
When counting, the most difficult thing is what is dozens plus nineteen plus 1. According to the counting principle of "full 1 decimal 1", 9+1= 10, so it should be more than the original ten digits1.
3 Describe the size relationship
On the basis of comparing the size of numbers in 100, children are asked to use words such as "more", "less", "much more" and "much less" (or "bigger", "much smaller" and "much smaller") to describe the size relationship between two numbers in 100. First of all, we should make clear the meanings of these words: "more" means more, "less" means less, "much more" means much more, "much less" means much less, and "almost" means a little more or less, which is very close. When describing the relationship, we should choose it reasonably according to the difference between the two numbers. For example:
50 to 45 (larger), 85 to 45 (much larger), 10 to 45 (much smaller)
4 Distinguish between odd and even numbers
Singular numbers refer to 1, 3, 5, 7 and 9, and even numbers refer to 0, 2, 4, 6 and 8. To distinguish whether a number is singular or even, just look at the number in the unit of this number.
Pay attention to calculation and lay a solid foundation.
1 review of oral calculation
The oral calculation of "I (II)" mainly includes abdication subtraction within 20, addition and subtraction of integer ten, addition and subtraction of integer ten, addition and subtraction of two digits of integer ten and addition and subtraction of two digits of integer ten.
In these oral calculations, abdication subtraction within 20 is the basis, in fact, it should also include carry addition within 20 learned last semester. Because these oral calculations are the key to learning one-digit plus two-digit (carry) and one-digit minus two-digit (abdication), and of course they are also the key to written calculations. Therefore, it is very important to calculate the carry addition and abdication subtraction within 20 correctly and skillfully. When practicing oral arithmetic, it can appear in the form of exercise groups. If you see 13-8=5, you will immediately think of 13-5=8 and the corresponding addition formulas 5+8= 13 and 8+5= 13, which can greatly improve the efficiency of oral calculation.
The key point is to correctly and skillfully calculate the two digits to be carried plus one, and the two digits to be abdicated minus one. The difficulty lies in understanding the operation and processing methods of "full 10 forward 1" and "back 1 forward 10". Of course, when reviewing, the key is to understand the difference and relationship between two digits plus one digit carrying and not carrying, two digits minus one digit abdicating and not abdicating, two digits plus one digit plus ten and minus ten. Comparison can also be made in the form of question groups, such as:
Two digits plus one digit, if the sum of digits is less than 10, then the sum of the digits on the ten digits is the number on the ten digits; If the digits add up to 10, then the number on dozens of digits is 1.
Two digits are subtracted by one, and if the single digits are reduced enough, the number in the tenth place of the minuend is the number in the tenth place; If the number of digits is not reduced enough, the number on a dozen digits will be smaller 1.
Adding and subtracting one digit from two digits means adding or subtracting two digits first; The addition and subtraction of two digits to an integer decimal number is to add and subtract the digits on the decimal number first.
Strengthen the comparison, clarify the methods, properly carry out time-limited training, and gradually improve the ability of oral calculation.
2 Review of written calculations
The pen calculation of one (base) mainly includes: two-digit plus two-digit carry addition and no-carry addition, two-digit minus two-digit yield subtraction and no-yield subtraction.
The key point is to clarify the written calculation method of adding and subtracting two digits: ① alignment with the same number; ② Count from the unit; ③ The digits add up to 10, and enter 1 into ten digits; The number of digits is not enough to reduce. If it is 1 from the decimal place, it will be reduced to 10 again.
The difficulty is that in the actual calculation process, children are particularly easy to confuse carry and no carry, abdication and no abdication. Therefore, when the units add up to 10, when the units add up to 1, the carry "1" should be marked. Remember that ten digits must be added up; When the number of digits is not reduced enough, the number of digits will be reduced from 1 to 10, and the abdication point cannot be forgotten, so when calculating the number of digits, the number of digits will be reduced by 1. Of course, you must not "gild the lily" when you don't need to carry or abdicate.
Similarly, written arithmetic training can also help children gain more experience from problem sets:
3 evaluation review
In oral and written calculations, estimation is usually used for prediction before calculation.
For oral calculation, more estimates are more than dozens, such as:
Greater than 37+8 () and greater than 46-4 ().
More than 40+39 () and more than 78-50 ().
To estimate the addition or subtraction of a two-digit number, we must first look at the addition or subtraction of a single digit. If you add or abdicate, the number on the ten digits will change accordingly. To estimate the addition and subtraction of two digits into ten digits, you can determine that it is greater than ten digits only by looking at the addition and subtraction of ten digits.
For written calculation, it is more important to say what the tenth digit of the number is, and then calculate the verification.
Two digits plus two digits or two digits MINUS two digits depends on the addition and subtraction of digits, and then the digits are determined according to whether there is carry or abdication.
Understand plane graphics and application.
In the first part, on the basis of intuitive understanding of simple three-dimensional figures such as cuboid, cube, cylinder and sphere, we mainly intuitively understand rectangle, square, triangle and circle from body to face. When reviewing, the key point is to be able to understand rectangular, square, triangular, circular and other plane graphics, and to solve some comprehensive problems.
When recognizing these plane figures, the most difficult and error-prone thing is to distinguish between rectangles and squares. Although the first-grade children don't need to tell the characteristics of a rectangle and a square completely, they can be guided to distinguish clearly from the side length: the four sides of a square are equal in length, while a rectangle is only the opposite length of two sides.
The comprehensive theme mainly includes:
(1) Classification chart: You can mark "?"with the number of edges. On the chart. The way, let us not repeat, not missing.
(2) Find the pattern and continue painting: First, find out the patterns arranged in patterns, and make several patterns into a group and circle a group of patterns, so that you can continue painting as smoothly as you see!
Such as: □△ ○ □△ _ _ _ _ _ _ _.
(3) Number of numbers: first find the most basic unit, then observe whether two or three numbers can be used to form a larger number in turn, and finally add up the numbers. Of course, sometimes we should pay attention to the direction of assembly.
For example, there are (5) squares. (4) Operation: Be sure to let the children throw a stick and fold an origami, so that they can feel it intuitively and vividly, and then they can think more deeply. For example, I know that a square piece of paper can be folded into rectangles, squares and triangles at a time; It takes at least four sticks of the same length to make a square.
Flexible use of "Jiao Yuan powder" to learn to shop.
The unit of "Yuan, Jiao and Fen" is a difficult point in the whole book, because the first-grade children rarely touch RMB and have little experience in independent shopping in their lives, so it has always been a headache for children, parents and teachers. In this unit, in addition to letting children know about RMB, its unit and the speed of progress, the key and difficult point is to let them learn simple practical problems in shopping activities. This involves not only the difference of different denominations of RMB, but also mathematical activities such as withdrawing money, changing money, paying money and changing money.
1 memory rate
"1 yuan = 10 angle, 1 angle = 10 point, 1 yuan = 100 point" these elements, angles and points should be very familiar. Only by memorizing the promotion rate can we convert and compare different units of RMB well.
For example, 8 yuan's 7 angle = () angle, because 1 yuan = 10 angle, 8 yuan is 8 10 angle, that is, 80 angle, 80 angle +7 angle =87 angle; 38 points = () angle () points, full 10 points is 1 angle, three out of 38 points 10 points are 3 angles, and there are 8 points left, so 38 points are 3 angles and 8 points.
When comparing the size of RMB, the unit should be unified before comparison, such as: 1 3.90 yuan, and the unit should be unified as "angle" before comparison. But sometimes we can use the method of "the data is the same as the unit", for example, the 30-angle 30 yuan is all 30, as long as it is larger than the two units of "angle" and "yuan". Sometimes it is enough to compare only a few dollars, for example, 7 yuan is 50 cents, and 6 yuan is 80 cents. Just compare the sizes of 7 yuan and 6 yuan to determine the final size. Therefore, we should master the comparative methods and use them flexibly.
2 accurate currency exchange
The principle of RMB exchange is fair, so the total denomination of RMB before and after exchange cannot be changed. If you encounter a large denomination, you can draw a picture to calculate it.
Pay special attention to different ways of changing money: for example, 1 50 yuan can be replaced by () 20 yuan and () 10 yuan, or () 20 yuan and () 10 yuan. In this case, we can think about it in an orderly way: if only 1 20 yuan is changed and the rest are changed to 10 yuan, then three 10 yuan are needed; If two 20 yuan are 40 yuan, then 1 10 yuan; If you change three 20 yuan tickets, you will be in 60 yuan, which has already surpassed 50 yuan, so you can't change them.
Also pay special attention to different statements when changing money, such as:
① 1 Zhang 100 yuan can be exchanged for () Zhang 50 yuan, () Zhang 20 yuan and () Zhang 10 yuan.
② 1 Zhang 100 yuan can be exchanged for () Zhang 50 yuan, () Zhang 20 yuan and () Zhang 10 yuan.
These two problems seem to be the same, but they are actually different. The first small problem is to change 100 yuan into 50 yuan, or 20 yuan, or 10 yuan; The second item is to change 100 yuan into three different denominations of 50 yuan, 20 yuan and 10 yuan, totaling 100 yuan.
3 shopping problems
To solve the actual shopping problem, we must clearly analyze the quantitative relationship in the problem and make the key points clear: money paid-used money = recovered money, money paid-recovered money = used money, used money+recovered money = paid money. Clear known conditions and problems, flexible choice of quantitative relations to solve.
In fact, in order for children to truly understand and master shopping problems, they should be allowed to go to real shopping situations. Under the supervision of parents, try to shop independently, experience the process and accumulate experience.
05 clarify the quantitative relationship and solve practical problems
In the problem-solving part, it is important for children to deepen their understanding of the relationship between quantity, communicate the links between practical problems, and cultivate and improve their ability to analyze and solve problems. In the first (second) textbook, the new types of problem solving are: simple practical problem of finding the minuend, simple practical problem of finding the minuend and simple practical problem of finding the difference between two numbers.
(1) The simple practical problem of finding the minuend is often reflected in finding the original number and a * * *. As long as we combine "moving" with "staying", we can find the "original".
(2) The simple practical problem of subtraction is often reflected in how much you eat, how much you sell, how much you borrow and how much you take away, which can be simply called how much you have removed. As long as the "original" is subtracted from the "surplus", it is "division"
(3) There are various ways to find the difference between two numbers, whether it is "how much () is greater than ()", "how much () is less than ()" or "how much () is equal to () if you remove a few", you can find the difference between two numbers by subtracting "decimal" from "large number".
Of course, in solving problems, we should learn to ask mathematical questions from different angles. In the process of finding and solving problems, we should constantly improve the ability to process and process information, especially gradually cultivate the ability to flexibly select and combine information according to problems.
Then, after such combing, are the children's review ideas clearer? Remember, it is also necessary to combine the actual situation of children's own learning, tailor-made and focused, so as to play a practical and effective role.
Top Ten Mistakes in Senior High School in 2006
Error-prone 1
Xiao Lin has just enough money to buy a toy car in 58 yuan. What is the maximum amount of RMB 10 for Kobayashi?
Children often ask, "Kobayashi 58 yuan bought a toy car and gave it to 10 yuan. How much did he pay at least? " Confused. Comparatively speaking, "pay at least a few 10 yuan" is easy to understand. Children will keep trying and correcting themselves: you can't buy a toy car for 50 yuan 10, but you have to pay 6 yuan 10 for 60 yuan. Therefore, when encountering the above problem, it will often subconsciously turn into a problem of "at least pay 10 yuan". The above question requires "how many 10 yuan at most", and the key is to understand the meaning of "just enough to buy". "Just enough to buy" means that Kobayashi's money is neither too much nor too little, that is, 58 yuan, but in 58 yuan, there are only five at most 10 yuan. If you think there are at most six 10 yuan, then Kobayashi has at least 60 yuan's money. How can it be "just enough to buy"? Therefore, it is quite helpful to learn the key words in the analysis questions.
Miss Wang's money is only enough to buy a volleyball from 65 yuan. How much RMB does Miss Wang have at most 10?
Error-prone 2
The question of consultation should belong to "counting money", that is, how much money a person has. Children are generally a combination of several yuan and several yuan, several angles and several angles, and often "(1) yuan (1 1) angle" appears. However, in real life, there is no such statement. Generally, the angle of 10 will be converted into 1 yuan, so it should be "(2) yuan (1) angle". When counting coins, you can circle RMB with 10 or 10 to remind yourself that it can be converted into larger units, so it is not easy to make mistakes.
Error-prone 3
Dongdong folded 40 paper cranes, and obviously folded 28 paper cranes. How many paper cranes must be folded to surpass Dongdong?
Children will attach importance to the word "at least", but often ignore the word "beyond". Most formulas: 40-28= 12 (only). I think this question is to find out the difference between Dongdong and a paper crane that is clearly folded. In fact, the word "at least" is very important, and the word "over" is equally important! If Ming Ming folds 12 paper cranes, then his paper cranes are also 40. It can only be said that there are as many paper cranes as Dongdong. The problem is that Mingming has more paper cranes than Dongdong, and the number of folds is the least, so we think Mingming only needs one more paper crane to surpass Dongdong. The answer should be: 40-28= 12 (only), 12+ 1= 13 (only). There are several key conditions in the problem, none of which can be ignored!
Xiaohong and Xiaowen practice skipping rope. Xiaohong jumped 46 times and Xiaowen jumped 53 times. How many times can Xiaohong jump at least to surpass Xiaowen?
Error-prone 4
There are 50 volleyballs in the school, 24 in grade one 18 and grade two. How much is a * *?
When three conditions appear in the question, some children will be at a loss, and even think that the top 50 and 18 are borrowed numbers. Actually, we can start with the problem. The question requires "how much to borrow from a * * *", so as long as the sum of the first-year loan and the second-year loan is a * * *. "There are 50 volleyballs in the school" in the question has no effect on solving this problem, and it is an unnecessary condition. Therefore, we should be good at clarifying the relationship between quantity and quantity according to the question and choosing the appropriate conditions to answer it.
There are 55 fairy tale books in the Practice Bookstore, of which 23 were sold in the morning and 18 in the afternoon. How many books have a * * sold?
Error-prone 5
Schools must plant 26 trees on both sides of the road. A * * *, how many seedlings do you need?
The problem of consultation lies in the misunderstanding of the sentence "26 trees planted on both sides". In fact, a simple icon can be drawn to help children understand, as shown in the figure:
"Planting 26 trees on each side" means planting 26 trees on one side and 26 trees on the other. So as long as the saplings on both sides are together, it is a problem of seeking. Sometimes, simple charts can help us understand the meaning of the problem more clearly. Painting is a good way.
To practice greening, workers' uncles should put 28 pots of green plants on both sides of the street. How many pots does he have to put in a pot?
When children see this problem, they often choose the second option without hesitation, because it is estimated that it is influenced by the topic of 24+( )=3 1. In fact, the key to this problem is to look at the ">" in the formula clearly. The number of the formula on the left is greater than 3 1. If 7 is only equal to 3 1, a number greater than 7 is required. It is necessary to read the questions clearly and analyze them in order to answer them correctly.
Error prone 7
Ten digits, the number before 40 is (), and the number after 90 is ().
Children are easy to fill in: ten digits, the number before 40 is (39), and the number after 90 is (4 1). The reasons are as follows: first, there is no way to read the numbers clearly, and it is "ten land numbers" instead of "one land number and one land number"; Second, I think we should ask a number before 40, and then ask a number after 40. Therefore, the examination questions must be carefully circled.
A place to practice counting ten. The number after 55 is (), and the number before 55 is ().
Error 8
Two digits have six numbers. There are () such two digits, and the largest is ().
Children who ask for counseling think that there are two digits like (10), and the biggest one is (96). Their figures should be: 6 16, 26, 36, 46, 56, 66, 76, 86, 96. I think I meet the requirement of "six figures", but I just ignore the qualification of "two figures", which is a common mistake made by children. Pay more attention when reading the questions, and never be careless.
Practice a two-digit number, where the ten digit is 3. There are () such two digits, and the smallest is ().
Error 9
A book has 68 pages, but you can read 35 pages every day. Can you finish it in two days?
What puzzles children is the meaning of "reading 35 pages a day" and asking "can you read it in two days?" Not knowing where to start is a big reason for this problem to go wrong. Reading 35 pages a day means reading 35 pages on the first day, 35 pages on the second day and 35 pages on the third day. The number of pages read every day is the same, all 35 pages. Ask, "Can you finish reading it in two days?" In fact, you only need to combine the number of pages read on the first day with the number of pages read on the second day, calculate the total number of pages you read in two days, and then compare it with the total number of 68 pages in this book. If the number of pages read in two days exceeds 68 or happens to be 68, it means that it can be read in two days; Otherwise, I can't finish it. Being good at analyzing and understanding the meaning of questions is of great help to the smooth answer.
Practice 70 pages of a book, and Xiaowen reads 22 pages every day. Can you finish it in three days?
Yi CuO 10
Xiao Lin, Xiao Ming and Xiao Hong all have some photos. Among them, Xiao Lin has more pictures than Xiao Ming, and Xiao Ming is much less than Xiao Hong. Who has the most pictures among them?
The mistake of this question is that I can't understand the relationship between the three pictures. The first condition is that there are more Xiaolin than Xiaoming, and the second condition is that Xiaoming is much less than Xiaohong. I feel a little confused and can't figure it out. In fact, the second condition can be changed to "Xiaohong is much more than Xiaoming". In this way, Xiao Lin is compared with Xiao Ming, Xiao Hong is also compared with Xiao Ming, and Xiao Lin and Xiao Hong are both compared with Xiao Ming. The object of comparison is clear, and the conclusion is clear: compared with Xiao Ming, Xiao Lin is only a little more, while Xiao Hong is much more, so Xiao Hong should have the most pictures. Sometimes, to put it another way, it's clear.
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4. First-year math teacher review plan
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