1, master the calculation method of integer plus one digit and the corresponding subtraction.

2, can accurately calculate the integer plus one digit and the corresponding subtraction.

Emphasis and difficulty in teaching

Make students master the calculation method of integer ten plus one and the corresponding subtraction.

According to the composition knowledge within 100, let students understand arithmetic and calculate accurately.

teaching tool

Courseware, sticks.

teaching process

First, review the introduction.

1, fill in the blanks:

(1)40 contains () ten digits;

(2)45 contains () tens and () ones, 4 tens and 5 ones are ();

(3) There are () tens and () ones in 38, and three tens and eight ones are ().

2. Courseware shows oral calculation questions:

①6+3= ②5+8=

③9-4= ④ 15-7=

⑤8+9= ⑥ 15-6=

⑦ 14-6= ⑧4+6=

Second, explore new knowledge.

1, stimulating imports

Just now, everyone was very skilled in addition and subtraction within 20. In this lesson, we will learn the addition and subtraction of numbers greater than 20. Are you confident to learn well?

Step 2 design the situation

One day, Xiao Ming and his mother went to the supermarket to buy notebooks. Mother was going to buy 30 books, but when she paid, Xiao Ming took two more books on the shelf. How many notebooks does mom have to hand in after that? How to solve this problem?

Answer on the blackboard: 30+2=

(1) Swing with a stick

Please take out 30 sticks representing 30 books. Why did you all take out three bundles of sticks? (3 bundles represent 3 tens, blackboard writing: 3 tens)

Take out two sticks to represent two books. (2 sticks represent 2 1 and the blackboard represents 2 1)

Please consider these two parts together. How many sticks are there in a box? Who can tell you what they think?

See what the elf thinks? Are you thinking the same thing as us? (30 is three tens, 2 is two ones, and three tens and two add up to 32, so 30+2=32)

(2) If mom bought 60 copies and Xiaoming took 3 copies, how many copies would they pay? How to calculate the formula?

Answer on the blackboard: 60+3=

Everyone can count 30+2. Can you count 60+3? Let's talk about the algorithm first. Who wants to tell everyone what they think?

(3) feedback exercises

Say the algorithm first, then the result.

30+4= 20+8= 50+2=

3. If my mother bought 32 writing books and found that there was not enough money when paying, how much should Xiao Ming pay to return 2 books? How to calculate in the form of columns?

Answer on the blackboard: 32-2

(1) Please wave it with a stick and try to work out 32-2=?

Who wants to tell you what they think?

Does the elf think like everyone else? 32 is three tens and two ones. Subtracting 2 means removing two 1, leaving three 10, which is 30, so 32-2=30. )

(2) If mom originally bought 63 copies and returned 3 copies when paying, how many copies should she pay? How to calculate in the form of columns? (63-3)

Please do the calculation yourself first and tell your deskmate your calculation method.

(3) feedback exercises:

Say the idea first, then the number: 56-6= 98-8= 74-4=

4. Guide students to think.

2+30=? How should I calculate it?

If students have difficulties, you can guide them to swing with a stick and let them understand the logic. 2+30 means that two 1 and three 10 add up to 32. Use case 8? 30+2? Only the position of the addend is different, and the algorithm is the same.

(2) feedback exercises:

3+60, 9+80, 7+20, 5+40, first, then the numbers.

Make up several similar oral arithmetic problems in the exercise book, and then turn around. Let the students think and see what they can find. (The addition positions of the two numbers are opposite, but the calculation results are the same)

Summary after class

What did we learn about addition in this lesson? (It's all integers plus one, or two digits minus one), Teacher: Today we are going to learn two digits plus one digit and the corresponding subtraction. Write on the blackboard. Combined with the calculation of the above example, how to calculate the integer plus one digit and the corresponding subtraction.

homework

Fill in the blanks.

1 and 34 have () ten and () one, three tens and five ones.

On Sunday, mother cat and kitten went fishing together. They caught 38 fish, of which the mother cat caught 30. Think about it, the kitten caught ().

There are () ten and () one in 3 and 46.

There are five tens and nine ones in ().

5. The number with 5 in ten digits and 2 in one digit is ().

6. There is a two-digit number, and the digit number is 3. The number on the tenth digit is 2 more than the number on the digit, and this number is ().

7. Of the six numbers 12, 36, 50, 34, 18 and 90, the number less than 36 is (), the number greater than 36 is (), the number greater than12 and less than 34 is (), and () is much greater than 50.

Second, compare who is faster to whom.

70+8= 40+4= 75-5=

83-3= 90+8= 30+7=

4+70= 67-7= 80+6=

Third, use column calculation to solve problems in life.

1. Fifty bicycles were parked in the parking lot, and nine others were brought in. How many are there in a * * *?

There are 36 pots of flowers in the greenhouse, and 6 pots have been removed. How many pots are left?

There are 40 students and 3 teachers. One bottle of mineral water per person, is it enough to bring 40 bottles?

4. Xiaoming cuts 50 stars, Xiaodong cuts 7 stars, and there are 54 students in preschool. Did they cut enough stars for everyone?

Write on the blackboard.

Two digits plus one digit and the corresponding subtraction.

Integer ten plus one and the corresponding subtraction teaching plan (2) teaching objectives

1, knowledge and skills target:

(1) combined with the understanding of logarithm, students can master the calculation method of adding a number to an integer ten and the corresponding subtraction, and can skillfully perform oral calculations;

(2) Consolidate the composition of numbers, infiltration subtraction is the inverse operation of addition, and get a preliminary understanding of additive commutative law;

(3) Apply what you have learned and solve simple practical problems.

2. Process and Method Objective: Let students go through the process of learning integer plus one digit and the corresponding subtraction, realize that there is mathematics everywhere in life, and let students experience learning mathematics in learning, and experience the learning method of group cooperative learning and the fun of using mathematics.

3. Emotion, attitude and values goal: Let students feel that there is mathematics everywhere in their lives in their study activities, let students experience the fun of learning and using mathematics in their study, cultivate their spirit of active exploration, stimulate their interest in learning mathematics and cultivate their confidence in learning mathematics well.

Emphasis and difficulty in teaching

Teaching focus

Students have already had the experience of calculating addition and learned the composition of numbers within 100. The combination of the two. Know the arithmetic of integer ten plus one digit and the corresponding subtraction? It is the focus of this class.

Teaching difficulties

Describe the calculation process of integer plus one digit and the corresponding subtraction, understand the meaning of the formula, and use the knowledge learned to solve simple practical problems.

teaching tool

Ppt courseware

teaching process

First, review the basics.

1. Today the teacher brought an old friend to everyone. Look, here he comes!

Courseware presentation: 30 self-introductions.

Can you help her find dozens of other friends?

Please read the whole ten numbers within 100 in ascending order.

2. The courseware shows several babies introducing themselves.

The students did a good job. Some babies have heard that they have come to our class. Can you help them introduce themselves?

Courseware animation demonstration: 57 69 85 66 22 32

There are several babies who came to our class before they were born. Guess who they are?

The courseware shows the baby's self-report and the students guess the numbers.

Second, create situations and learn new knowledge.

1. Teachers create situations.

(1) Transition: The students performed really well. The teacher decided to buy some books for everyone as a reward. What did you say?/Sorry?

(2) The courseware shows the teacher's purchase of writing function books. The assistant aunt gave the teacher 2 copies first and then 30 copies.

Please observe carefully and say what you know about mathematics.

(3) Based on this information, who can ask questions?

Health 1: How many copies did you buy?

How much did it cost to give birth to 2: 1 * *? I will solve it after learning the knowledge of RMB. )

S3: Give the teacher two copies first. How many copies are left?

Encourage anyone who can ask math questions according to this specific situation. )

Through courseware display, students can be brought into vivid life situations, which can stimulate their interest in learning, encourage positive thinking and cultivate their awareness of thinking and asking questions frequently. ]

2. Solve 30+2 and 2+30.

(1) Teacher: Students really use their brains and come up with so many questions. If you want to know: How many copies did Yi buy? How should I calculate it?

Students are formulated orally, and teachers write on the blackboard: 30+2=32 2+30=32.

(2) Why do we use addition calculation?

After the students answer, the teacher summarizes.

(3)30+2 equals 32, right? Please use the learning tools in your hands to calculate and talk about your ideas in the group. Start now!

(4) Reporting algorithm:

① Dial the counter: dial the three beads in the tenth place first, and then the three beads in the first place, which is 32.

Put a small stick.

When students report, they should be guided to say how many tens and how many ones. )

(5) Can you work out 30+2 without learning tools?

Student report.

A. Number method: 30 is followed by 2, which is 32, so 30+2=32.

B. the composition of numbers: three tens and two ones make up 32.

C:

(6) Optimization algorithm: Everyone thinks there are many good methods, so which one do you think is the most convenient to use?

Guide the students to say that it is most convenient to calculate 30+2 with the composition of numbers.

Let the students understand that listing 30+2 is based on the meaning of addition, combining 30 and 2, and the result of calculating 30+2 is based on the composition of one hundred, and three tens plus two add up to 32. ]

(7) q:? One * *, how many copies do you need? How else can you list addition formulas?

Teacher's blackboard writing: 2+30=

How to calculate 2+30? Who can say what they think?

Students say the algorithm and get the result.

(8) Classroom exercises. Seeing that the students are learning so well, let's have a small competition, shall we? Who can work out the following formula with the composition of numbers? Come on! There are small prizes waiting for you!

60+3= 30+8=

60+8= 50+8=

60+9= 90+8=

3. Solve 32-2= and 32-30=.

(1) Teacher: Just now, the teacher has given the students two prizes. How many books does the teacher have left? How should I calculate it?

(2) Students answered orally, and the teacher wrote on the blackboard: 32-2=30.

Q: Can you tell us how it is calculated?

There are three 10 and two 1 in 32. If you remove two ones, there are three tens left, which is 30. You can also think of addition and subtraction, because 30+2=32, so 32-2=30 and so on. )

(3) If the teacher takes three bags, how many bags are left? How are you going to solve it?

Students answer orally, and the teacher writes on the blackboard: 32-30=2.

There are three tens and two ones in 32. If you remove three 10, there are two 1 left, which is 2; You can also think of addition and subtraction, because 30+2=32, so 32-2=30 and so on. )

Third, consolidate the practice.

The students are great. They have learned to add an integer to a number and then subtract it quickly. The teacher will take the students to the math castle to play. Do you want to go?

But on the way to the castle, Cobra set up several checkpoints. Do students dare to break through?

Level 1: Put a stick, make a formula and tell me how you worked it out. (This book is 48 pages? Do it. Question 1)

The teacher put a stick on the physical exhibition platform. Let the students observe by themselves, list the corresponding formulas, and then calculate. Students will talk about how to calculate.

(1) Put five bundles first, then six bundles.

(2) Put 5 bundles of 6 roots first, and then take away 6 roots.

(3) Put 5 bundles of 6 roots first, and then take 5 bundles away.

The second level: (book 48 pages? Do it. Question 2)

Teacher: Mother Bear took Baby Bear to the grassland. Mother bear sets up the oven to bake the baby's favorite corn. Baby bear drools at the smell. He really wants to eat sweet corn at once. But mother bear is not in a hurry. She asked her baby to use his brain. Whoever can find the same formula as the corn before can eat the corn first. Can you help Bear?

Students answer orally and finish collectively.

The third level: the little bee goes home.

On the way to the castle, cobra also released a group of lost bees. Can you take them home?

Put the formula on the bee and the bee can go home!

The fourth level: solve the problem.

Show the scene of two people talking in the textbook, and let the students express their opinions after reading it.

Talk about your thoughts. Students who can use formulas can use formulas.

Students report and the teacher's courseware shows the whole process.

The students have successfully broken through the Cobra checkpoint and the gate of the castle is about to open. Let's see what's in the castle.

Grandpa Wisdom has prepared many fruits of wisdom in the math castle. Whoever can work out the formula on the fruit of wisdom, give it to him.

The courseware shows the tree of wisdom, and students answer the formulas on the fruit of wisdom. If the calculation is correct, reward him with the fruit of wisdom.

Fourth, class summary.

Teacher: What did you learn in this class? Talk about your gains.

Students are free to talk about gains.

Class is over.