Primary school mathematics micro -course teaching design dual digits plus one digit, a total of ten numbers

Subject

Double digits plus one digit, a total of ten numbers

Designer

Shi Beibei

source

First grade

Design time

20 **. 4

Recording method

PPT demonstration

duration

5 minutes

design concept

Double -digit plus one digit and a dozen numbers is an important computing understanding that allows students to use micro -courses to be more conducive to students’ calculations, understanding and mastering methods. A better understanding of the method of mastering and mastering has achieved more effort.

teaching objectives

1. Knowledge and skill goals: two digits plus one digit, a total of ten calculations, through speculation, operation, verification, discussion, and induction, so that students can experience the evolution of calculations.

2. Methods and process goals: In the process of exploring the two digits and one digits, the process of the evolution of the consideration

3. Emotional and attitude goals: Through the evolution of algorithm, cultivate students’ operations, observation, analysis and computing capabilities.

Difficulties and key

The understanding and application of calculation

teaching method

Theoretical teaching

Micro -class teaching process design

Link

explain

plan for design

Import

Review

Classmates, today we will learn two digits plus one digit, a total of ten numbers. First of all, let’s do a set of exercise questions

20+20 = 60+30 = 50+40 = 20+7 =

40+5 = 30+8 = 10+9 = 50+7 =

Looking closely for this group of exercise questions, what are the characteristics in the calculation process? The entire dozen additions add dozens of digits. Dozens of dozens of or dozens and several are more than dozens. Not only are you good at moving your brain, you must also observe it carefully. Let’s solve mathematical problems together!

Lay the basis for the calculation method

process

Second, cooperation inquiry.

Teacher: Seeing Xi Yangyang in the calligraphy class, Xi Yangyang said that I have written 25 words, and there are 2 words that I have not written. I have written 20 words in lazily. What mathematics do you ask, how many words do you want to write?

Seeking a total of total, calculation with additional method

25+2 =

How to calculate?

First of all, we use a small stick to set up a solution, first place 25 small sticks, put 2 roots, combine 2 and 5 roots, 5+2 = 7 and 20 root are 20+7 = 27

Is there any other way?

You can also score 25 into 20 and 5, first calculate 5+2 = 7

Calculate 20+7 = 27

Like 25 points into a total of ten and one digit, first add two digits, plus the entire ten, this method is called the “split method”

Think about it, what should we pay attention to when calculating the two -digit number and one digit number?

The addition of the same digit is to add the number of the two digits to the one digit before adding a total of ten numbers

What else can I ask?

How many words did Xi Yangyang write in total?

Seeking a total of additional methods

25+20 =

How to calculate?

Still put a small stick first, put 25 roots first, then 20 roots, and 20+20 = 40 in 20 and 20 roots

40+5 = 45

Divide the double digits into a whole ten and one digit, first ten counts, and then add a number of numbers.

Think about it, what should you pay attention to during the calculation process?

The same number of digits adds two digits into a total of ten and one digit, adding ten to one digit, plus one digit.

What are the differences between 25+2 and 25+20?

Adding a bit is to add to the single place

Add a whole dozen numbers to add to the ten digits

Pay attention to the same digital addition.

32-5 = 27

Go away from 14 roots

First calculate 14-9 = 5

Calculate 30+5 = 35

Calculate these two sets of calculations

54-3 = 61

76-4 = 72

57-3 = 54

76-8 = 68

54-9 = 5

57-9 = 48

Observe the two sets of calculations, what do you find?

The first group is enough to reduce, the ten digits have not changed, it is not abdical reduction

The second group is not enough to reduce the digit. It is necessary to retreat from the ten positions, which is an abdication.

summary

Double -digit plus one digit (not in place), the same number of numbers in the same digit, that is, first add the number of digits to one digit with one digit, and then add a total of ten numbers.

Double -digit plus a total of ten numbers, the same number of the same digits, first divide the double digits into a whole ten and one digit, the whole ten

The number is added with the entire dozen numbers, plus one digit.

After -school reflection

1. Use exploration guidance in teaching methods.

2. In terms of production methods, I choose to use PPT demonstration and match appropriate explanations. I have made a careful preparation for each link of Micro Video to show students clearly.

Calculate 20+7 = 27