PEP compulsory education curriculum standard experimental textbook Grade One Volume Two Page 62 Example 2 and "Doing".

Second, the teaching objectives

1. Make students understand and master the oral calculation method of adding two digits to one digit, and be proficient in calculation.

2. In order to cultivate students' cooperative spirit, innovative spirit and inquiry ability, students independently explore various methods of calculating 24+9 and imitate 24+9 to write other carry addition formulas.

3. Through dynamic practice design such as mutual competition, cultivate their positive creative emotion and growing interest in mathematical knowledge, as well as their ability to self-evaluate and objectively evaluate others.

Third, the focus and difficulty of teaching

Emphasis: oral arithmetic method of two-digit plus one-digit carry addition.

Difficulties: Understand and master the carry rule of carry addition.

Fourth, teaching preparation.

1. Teachers prepare multimedia courseware, physical projectors, 2 vertical rows, 4 yellow squares (24) and 9 blue squares.

Each student should prepare a blank sheet of paper, a black marker, a group of squares and a discussion card for each group.

Teaching process of verbs (abbreviation of verb)

1. Create a situation

(1) computer animation: The story is about opening a bear shop in the forest! On this day, the little monkey went to the store and bought a book, 24 yuan, a pen and 6 yuan. Please help him figure out how much he should pay. Look! The little monkey was suddenly attracted by the beautiful table tennis bat, so he decided to buy a table tennis bat instead of a pen. He thought to himself, how much should I pay this time, 24 yuan 9 yuan?

(2) In response to the students' answers, Teacher: Is 33 yuan right? How to calculate it? Today we will discuss this problem together.

Explore and dispel doubts

(1) The teacher showed the discussion questions on the computer: Tell me how you worked out 24+9, show your thinking process with small squares, and tell your deskmate how you did it.

(2) According to the above steps, let the students discuss in the group and the teachers patrol.

(3) Communication verification. Let some students go on stage and talk about how they calculate 24+9. The computer reproduces its process one by one:

① Four small squares and nine small squares gradually get closer, and then they are enclosed by ""to display the number "13". Finally, two vertical squares (20) on the left are flashed.

② The 24 cubes are divided into 23 cubes and 1 cube, and the 9 cubes on the right and 1 cube are combined into a line, and the remaining 23 cubes are finally flashed.

(3) Divide 9 small squares into 6 and 3 parts, combine the remaining 24 small squares with 6 into 3 rows, and finally flash the remaining 3 small squares.

The teacher named these algorithms "XXX algorithm" after the speaker to show encouragement.

Teacher's explanation: Use whichever method you think is simple.

(4) discussion and display.

① The group discussed according to the discussion card. Question: Imitate 24+9, can you put another number in the first bracket of 24+()=3 () to calculate the number of the new formula? Compare which group has worked out the more correct formula.

After editing, observe and see what you can find from it.

24+()=3( )

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(2) Show the results of the compilation questions, and the teacher assigns several students to talk about what rules have been found.

Guided observation: Why did the two in the tenth place become three?

Summary: The figures in the unit add up to ten, and decimal plus one. 10 times 2 plus 1 get 3. Expressions like this are called carry addition. [Title on the blackboard: carry addition of two digits plus one digit]

(5) knowledge transfer

Q: Just now we learned that two digits plus one digit 24+9=33. Is there anything like this carry addition? [Blackboard: 9+24=33]

How do you know it is equal to 33? Can this formula still be compiled?

3. Consolidate and expand

(1) "Do it" on page 62. Q: What do you find by comparing these three formulas with those you just learned?

(2) Open a "two-wheeled train" competition: add 6 continuously. Can you tell the sum of each addition quickly? (Title 10 on page 65 of this book)

(3) spread divergence.

Let the students combine what they have learned today and use a black marker to calculate the questions freely on white paper. After calculating each other in the same place, please ask one or two groups of students to show the oral calculation questions on the stage so that other students can answer them first.

[Comment: "The sea is wide and the fish jumps, and the sky is high and the birds fly." In such a relaxed thinking space, all students are fighting for the first place, unwilling to lag behind, the classroom atmosphere is unprecedentedly active, and students' thinking has also developed freely. Because of their different abilities, they wrote different types of oral calculations and made correct calculations one by one. Some students want to test everyone and show that they are "better". They also deliberately put forward the carry addition problem of three digits plus one digit, and even the carry calculation formula of four digits plus one digit. After seeing the big numbers in the topic, the students subconsciously said "Oh", calmly thought about it, and were delighted to find that the original method of adding multiple digits to one digit was * * *. As long as the rules are mastered, the calculation is very easy. ]

(4) Transformation application.

Teacher: In fact, we often use the knowledge of two digits plus one digit in our life. For example, there are 29 students in the first five groups and 6 students in the second group in our class. Let you calculate how many people there are. Think about it, is there such an example around you? Talk to each other.

4. Meaning construction

(1) Teacher's summary: Today, students boldly used old knowledge and old rules to creatively explore a variety of oral arithmetic methods of multi-digit plus one-digit carry addition. Can you draw their oral arithmetic methods of three-digit plus two-digit and four-digit plus two-digit carry addition? Children, try it.

(1) Teacher: How many points are you going to give yourself in combination with your performance in this inquiry activity? What other aspects need to be worked hard? How many points are you going to give the teacher? Why?

[Comment: This design suddenly digs out the distance between teachers and students. In self-evaluation, students may not feel as good about themselves as teachers think. They can accurately and objectively see their own strengths and weaknesses, and make clear the direction of their next efforts. I think this is very valuable in the process of students' growth. In addition, while most students give their teachers affirmation and encouragement, the most rare thing is the opinion of a few students, "Teacher, it would be better if you had more sense of humor!" " ""Teacher, I hope you can let more timid students like me answer questions. "... these sincere expectations will spur teachers and children to make progress together! ]

General comments:

The teaching design of this course is quite innovative, which breaks through the usual teaching method of teaching in the order of textbook arrangement. Teachers strive to guide correctly, and students actively study, so that the whole learning activity becomes the whole process of students' active participation, independent inquiry and innovative thinking. In the whole process, I think the key to the success of teaching lies in whether students' subjective initiative is brought into play and they are constantly given successful experiences. The analysis is as follows:

1. Explore and explain, innovative thinking

First of all, when teaching example 2: 24+9, the teacher did not rush to lead the students to explain step by step, but provided discussion steps for everyone to discuss in targeted groups. The goal of exploration is how to calculate 24+9. The way to explore is to talk about your algorithm and take out a small square to verify its correctness. As a result, the calculation theory is explained and the calculation method is preliminarily obtained.

In the whole process of inquiry, students' thinking in images and abstract thinking complement each other, and the potential of group wisdom is fully exerted. There is even a spark of creative interactive thinking. Generate shines brilliantly, such as calculating 24+9, some calculate 4+9= 13 first, and then calculate 13+20=33, or think of 24 from 9+24=33. Others unexpectedly divided 24 into 23 and 1. First combine 1 and 9 into 10, and then combine with 23, or 9 into 6 and 3, 24 and 6 into 30, and then combine with 3. After verification, the teachers affirmed their ability of observation, analysis and hands-on inquiry and their innovative spirit, and the students enjoyed the joy of success.

2. Give play to the subjective consciousness and stimulate interest.

Stimulating students' interest in learning is an important condition to give full play to students' main role in cognitive activities. Therefore, in this class, starting from the age characteristics of the students, the teacher changed the traditional consolidation method and changed the static state into the dynamic state, so that the students could freely export the calculation questions on white paper with black colored pens in combination with what they learned today, and show them to the whole class after calculating each other at the same table, so that other students could answer first. It's really "the sky is vast, birds are singing and flowers are fragrant". In such a relaxed thinking space, students will inevitably compete for the first place and don't want to fall behind. Because of different abilities, students write different types of oral calculations and make correct calculations, which greatly improves their interest and confidence in oral calculations.

3. By analogy, migration and expansion.

In order to enable students to master the carry addition of two digits plus one digit deeply and accurately, after teaching 24+9, the teacher carefully designed an open-ended question 24+( )=3 (), asking students to fill in a number in brackets like 24+9 and calculate the number of new formulas. Students' creative enthusiasm was mobilized again, and everyone scrambled to say the compiled questions in the group, which just provided an opportunity for the following tips. Then the teacher struck the iron while it was hot and encouraged the students to observe the formula. From this, they found that the children soon found that all two of the ten digits became three, because the numbers in each digit added up to ten, and one was entered in the ten digits, which successfully broke through the difficulty of "carry". From this, I deeply feel that the main role of teachers is to create an open and harmonious environment for students' learning activities, so that their learning ability is greatly enhanced, and they can constantly discover, change and create in a complex social environment with a scientific attitude and method.

It comes from life and is applied to life.

As we all know, there is mathematics everywhere in life, so teachers attach great importance to cultivating students' consciousness and ability to solve practical problems by using mathematical knowledge. So, at the beginning of class, the teacher consciously created the situation that the little monkey bought a book, 24 yuan, a table tennis bat and 9 yuan, and didn't know how much it would cost, so that students could actively use their mathematical minds to explore methods and solve practical problems. In addition, at the end of the class, the teacher asked the students to connect with reality, citing examples of two-digit and one-digit carry addition in life, so that students could feel that mathematics knowledge is indeed widely used, and there are still many mysteries in life waiting for them to practice and explore.