Teaching objectives
1. Make students know the order of numbers within ten thousand more clearly and master the method of comparing the sizes of numbers.
2. Cultivate students' logical thinking ability and good study habits of doing things seriously.
Teaching focus
Will compare the size of numbers within 10 thousand.
Teaching difficulties
Correct use of greater than sign and less than sign.
Teaching process design
First, review the preparation.
Demonstration courseware? Compare the sizes of numbers (import)?
Q: Which tortoise is older? Why? (15 tortoise is older, because 15 is bigger than 9, 15 is a double digit, and 9 is a single digit. )
Continue to demonstrate the courseware? Compare the sizes of numbers (import)?
Teacher: At this moment, another turtle with the age of 5 1 climbed onto the beach. Compared with the tortoise with the age of 15, which tortoise is older? Why? (5 1 year-old turtles are older, because 5 1 is larger than 15, which is one tenth of the number, and 5 1 is 5, and 15 is one tenth of 1).
Continue to demonstrate the courseware? Compare the sizes of numbers (import)?
Teacher: At this moment, a 58-year-old tortoise climbed onto the beach. Who is older than a 5 1 year-old tortoise? Why? (58 is greater than 5 1, and the number in ten digits is the same. Compared with the number in one bit, the number in one bit of 58 is 8,5 1, and the number in one bit is1).
The teacher said: when we compare the age of turtles, we are actually comparing the size of numbers. (blackboard writing: compare the size of numbers) We have learned to compare the size of numbers within 100. Look at the number of digits first, and the number with more digits will be larger. If the number of digits is the same, look at the number on the tenth and the number on the tenth, and this number will be larger. If the number in ten digits is the same, it will be greater than the number in single digits.
Let's compare a few more figures:
6 1○56 45○47 100○98
The teacher said: after we fill in the greater than sign and the less than sign, we can use jingle to check whether the symbols are written correctly. Big mouth to large number, small tip to decimal number. We use the knowledge we have learned before to learn numbers within 10 thousand to see who can learn quickly and well.
Second, learn new lessons.
1. Classify according to the digits of the following figures.
Presentation mode:1230,965,395,1689,2005438+0,470.
The teacher asked: These figures are very large. Who can read them? You can guess which is bigger than the three-digit ratio or the four-digit ratio based on the knowledge of comparing the sizes of numbers within 100. Why? (Four digits are big, because the highest digit of four digits is thousands; The highest digit of three digits is 100, less than 1000).
Let's compare these figures:
Summary: Different digits are greater than the size, with more digits and less digits.
2. Compare the sizes of numbers with the same number of digits.
(1) Compare the sizes of 5640 and 8790.
The teacher asked: These two numbers are all four digits. How to compare? (first, compared with their highest position, 5 thousand is smaller than 8 thousand)
Summary: If the digits of two numbers are the same, compare them from the highest digit first.
Exercise:
965○395 395○470
1230○ 1689 1689○200 1
(2) Which car has more soda? 3864○3529
The teacher asked: 3864 and 3529 are all four digits, and the highest digits are the same. How to compare? (Compare the numbers in hundreds again)
3. summary.
The teacher said: compare the numbers within 10 thousand, look at the number of digits first, the number with more digits will be bigger. If the number of the same digits is greater than the size, the number of the maximum digits increases from the highest digit, and if the number of the highest digits is the same, it is compared with the next digit.
Third, consolidate feedback.
1. Fill in the greater than sign or less than sign in ○ below.
398○402 3940○5230 1020○999
2. Arrange the following figures in descending order.
( 1)94 1, 893, 100 1,9 14
(2)3005,3050,3500,3049
3. Find the largest and smallest of the following figures.
463,9528,4000,2089,9030,8006.
Maximum quantity: _ _ _ _ _ _
Minimum quantity: _ _ _ _ _ _
4. Write down the adjacent numbers.
Write five numbers after each number below.
196,798,2999, 1 187.
6. The largest four-digit number consisting of 2, 9, 0 and 5 is () and the smallest four-digit number is ().
7. Fill in the form.
8. Fill in the appropriate number in □.
45□& lt； 453362 & gt□797 10 & gt； 7□ 1
8□6 & lt； 86 152□& gt； 526 1000 >□999. Thinking.
56-7? 2=7? () 12-8 & gt； 12-() 40? 5 & gt()+4
Class summary.
Today, we learned to compare the sizes of numbers. Let's think about the comparison of numbers within 10 thousand. How to compare the size of numbers within 10 thousand?
Investigation activities
Compare who is the tallest.
Activity purpose
1. By comparing the heights, you can get more familiar with the size of the comparison numbers.
2. Exercise students' practical ability in activities and draw simple statistical charts.
3. Cultivate the spirit of mutual assistance among students.
Activities to be prepared
Prepare a few meters.
Activity process
1. Divide the class into several groups and give rice to each group.
2. Students in the same group measure each other's height and record their names and heights.
3. Students in the same group compare all the heights of the group and decide that the group is the tallest and the group is the shortest.
4. Compare the tallest and shortest in each group, and judge the top three and the last three in class height.