Mathematics teaching plan for the fourth grade of primary school Volume I: Fan Wenyi: Understanding of Computing Tools
Teaching objectives:
1. Make students know all kinds of calculation tools through teaching, and have a certain understanding of abacus and calculator.
2. Cultivate students' interest in learning mathematics.
3. Let students feel that there is mathematics everywhere in their lives.
Teaching emphasis and difficulty: understand the use of abacus, calculator and calculator.
Teaching emphasis: be able to use abacus and calculator by yourself.
Teaching aid preparation: abacus, calculator.
Teaching process:
Participation before class: Understand the relevant information of computing tools, get ready, and introduce the computing tools you know to everyone in the clearest way.
First, the history of computing tools
(1) Participate in feedback before class (students introduce calculation tools)
In front of us, we learned how numbers are generated. With the generation of numbers, there will be the calculation of numbers. In order to facilitate calculation, people invented various calculation tools. Before class, students inquire about relevant information. Who introduced you to the computing tools you know?
Students speak.
(2) The teacher supplemented the development history of computing tools according to the introduction of students.
The origin of computing tools can be traced back to the Spring and Autumn Period and the Warring States Period more than 2,000 years ago. The computing invented by ancient people in China is the earliest computing tool in the world. About six or seven hundred years ago, China people invented a more convenient abacus, which has been in use ever since. Many people think that abacus is the earliest digital computer, and abacus formula is the earliest systematic algorithm.
The appearance of slide rule pioneered the analog calculation. Since Gunter, people have invented many kinds of slide rules. It was not until the middle of the 20th century that the slide rule was gradually replaced by the pocket calculator.
During the more than 200 years from17th century to19th century, a group of outstanding scientists have successively developed mechanical computers, among which Pascal, Leibniz and Babbage are the representatives. Although the structure and performance of computers in this period are still very simple, many principles and ideas embodied in them have begun to approach modern computers.
The oldest computing tool: calculation and preparation
China's calculation in the Spring and Autumn Period is the oldest calculation tool in the world. When calculating, put it into vertical and horizontal graphs and represent any natural number according to the principle of vertical and horizontal alternation, so as to carry out algebraic operations such as addition, subtraction, multiplication, division and square root. After negative numbers appear, there are two kinds of dividends: red chips are positive and black chips are negative. This kind of operation tool and method was unique in the world at that time.
China invented the abacus.
With the development of computing technology, it is more and more inconvenient to solve some more complicated mathematical problems. So about six or seven hundred years ago, China people invented the abacus, which combined the decimal counting method and a set of calculation formulas and has been used ever since, and is regarded as the earliest digital computer by many people.
The general abacus is mostly made of wood, and the beads are also made of wood. Later, it was developed to use copper and other metals to make abacus. The high-end abacus is made of jade. In addition to cylindrical beads, there are also beads with rhombic cross sections. Our abacus is several meters long and the smallest is only a few centimeters.
The abacus can perform various operations, such as addition, subtraction, multiplication and division. Up to now, the addition and subtraction speed of abacus is no less than that of calculator.
The beads on the abacus move up and down, left and right, so that the calculator can intuitively see the operation process of addition, subtraction, multiplication and division. The rhythmic sound made by the collision between counting beads and counting beads, and between counting beads and rungs constitutes a wonderful "calculation March". Calculator feels the fun of calculation from the sound. These happy moods are reflected in the saying "strike three strikes and strike two strikes", "whatever" and "split the accounts".
When calculating with an abacus, you should not only move the beads with your fingers, but also look at the numbers with your eyes and keep thinking. This is a very typical combination of hand and brain, and it is a good way to improve intelligence and develop the right brain. Some scholars point out that learning abacus and practicing fingers are effective ways to develop intelligence.
Because abacus has so many advantages, it has been used in China for more than two thousand years and is still widely used all over the world. In Japan, South Korea and Southeast Asia, which are deeply influenced by China culture, the teaching and popularization of abacus technology have been paid attention to. Japanese primary school students list reading, writing and abacus as three basic skills, and abacus education in Japan is in a position in the world. There are as many as 35,000 abacus schools in Japan. The abacus education in South Korea has also made great progress in recent years.
Even Brazil, as far away as South America, has set up the abacus alliance, which holds four abacus assessments and two abacus competitions every year. Mexico in North America has a national abacus branch, and the United States has an abacus education center. More than 65,438+0,000 schools receive abacus education, and abacus is becoming a mathematics teaching tool in the United States.
computer
After several years' efforts, the University of Pennsylvania has developed the world's first electronic computer-ENIAC. With the progress of science and technology, computers are constantly updated. At present, fast computers can calculate hundreds of trillions of times in 1 second. The size of the computer has also changed a lot. The first computer in the world was about the size of a room. Now there are desktop computers, notebook computers and palmtop computers.
History of computer development:
1946, an epoch-making event happened in human history, and the first electronic computer was born.
The first generation of electronic computers characterized by the use of electron tubes made great progress in the late 1940s and early 1950s.
The second generation of computers came out in the mid-1950s, replacing electron tubes with transistors and adding floating-point operations.
1964 IBM360 system came out, which became the representative of the third generation electronic computer with integrated circuits.
■ The fourth generation computer using VLSI.
■ The fifth generation electronic computer is called intelligent computer.
The successful development of a neural computer that imitates the function of the human brain indicates that the development of electronic computers has entered the sixth generation.
Second, the understanding and use of abacus and calculator
1. abacus
Just now, students introduced many computing tools, among which abacus is unique to China, and it can still be seen in many places now. Do you know the abacus? How much do you know about abacus?
(1) abacus part name
A beam is installed in the rectangular frame of the abacus, and several sticks are drilled on the beam, which is called a file. Wear a string of beads on each string, which is called abacus or beads.
The common abacus is two beads on the beam, each representing five; Five are under the beam, one for each person. When calculating, dial the abacus according to the prescribed method to get the calculation result.
When dialing the number, you should first set the number, specify which file it is, and then dial the number. (The third gear from right to left is designated as a unit)
Set aside a number and say how significant it is.
(2) Two different abacus:
Show two different abacus (picture on page 23 of this book):
Observe the differences.
The abacus on the left is China's abacus, and there are two beads on it, each of which represents 5.
Later, the abacus developed to Japan, and gradually evolved into a positive edge and a bead.
The reason is that China originally adopted the radix system of 16, and entered 1 when 15, so each file of the abacus is15; Decimal system was adopted after entering Japan, so there are 1 bead left on the abacus.
(3) Two functions of abacus: calculation and counting.
2. Calculator.
(1) calculators are widely used. Do you know a calculator?
Show me a calculator. Can you tell me the function of each key?
Display screen, time key, date key, clear key, switch and clear screen key, storage operation key, bracket key, numeric key, operation symbol key, equal sign key, etc.
(2) Let the students read books by themselves and read calculators by themselves, and then communicate in groups.
(3) What are the advantages of calculators compared with abacus?
(4) Look at the calculator in the class and check the password between the teacher and the students.
Third, summary.
The use of calculators has brought us a lot of convenience. What function do you think it will have if you use a calculator? Let's find out if there is a calculator with this function and how to use it. We hope that students can use their intelligence to invent better computing tools.
Fourth, homework:
1. Continue searching for information about computing tools. Interested students, it would be better if you could list the computing tools according to their development history. )
2. Understand other functions of the calculator.
Mathematics teaching plan for the fourth grade of primary school Volume I: Model essay 2: Calculation with calculator
Teaching content: example 1 textbook page 26 example 2, doing.
Teaching purpose:
1. Enable students to do simple calculations with electronic calculators.
2. Let the students know that the order of calculation with an electronic calculator is the same as that of writing.
3. Let students be good at observing and discovering the secrets of mathematics, and be able to do oral calculations on some regular numbers.
Teaching emphasis: be able to use calculator for simple calculation.
Teaching difficulties: know how to observe and find some regular numerical calculations.
Teaching process:
First, use a calculator to calculate:
386+ 179=
Tell me how you use it.
(Press "386" first, the screen will display 386, then press "+",the screen display will remain unchanged, then press "179", the screen will display 179, and press "=" to display the result 565. )
Try what function the ce key has. (clear)
Try it yourself:
26×39= 3 12÷8=
Length What do you think should be paid attention to when using a calculator?
Look at the number clearly and don't press it wrong; Clear 0 before each calculation.
2. calculation.
54+46= 60×2=
198÷49= 50+30=
38×79= 20 1+99=
It's over. How did you calculate it so fast? It is not always possible to calculate with a calculator. For example, you don't need a calculator for problems that can be calculated directly with your mouth and simplified. )
3. Do some exercises.
Let the students do it in groups and then do it at the same table.
Second, it is observed that
1. Compare and see who did it quickly and correctly.
(Group of four)
9999× 1= 9999×2= 9999×3= 9999×4=
Tell me why you did it quickly and correctly.
Observing the above formula and results, what laws do you find?
Students speak freely.
Teacher: Based on your findings, make a bold guess. Can you write the answers to the following questions directly without using a calculator?
9999×5= 9999×7= 9999×9=
Teacher's summary: When you meet a natural number (except 0) within 9999 times 9, the answers are all five digits, the digits and units are the product of natural number and 9, and the middle three digits are all 9.
Third, practice.
Do it. Page 30 exercises 1 1 and 12.
The question 1 1 is conducted through a competition to consolidate students' use of calculators.
12 is independently completed by students and evaluated by the whole class.
Fourth, class summary.
What did you buy today?
How big is the first volume of the fourth grade mathematics teaching plan/kloc-0 10000000000?
Teaching content: 33-34 pages.
Activity objectives:
1. Through collecting data, operating experiments and discussing and communicating, let students experience the size of 100 million in specific situations, develop their sense of numbers and feel the close connection between mathematics and real life.
2. Get some problem-solving strategies and methods to develop students' problem-solving ability.
3. Get successful experience, and initially establish self-confidence in using mathematics to solve problems.
Activity focus: Let students practice their own operations and let them actively summarize the research methods.
Activity difficulty: How big is the spatial concept of 1 100 million?
Activity preparation: paper, books, rice, soybeans, etc.
Activity flow:
It includes four stages: design scheme-practice-summary-expression and communication.
The first stage: establish the problem design scheme.
1. Define the purpose and requirements of the activity.
Take the group as a unit, describe it by creating realistic situations and combining specific materials.
The scale of one hundred million, from which we can understand the scale of one hundred million.
2. Establish research questions.
Example: How much is 100 million grains of rice?
How much space does 100 million students take up together?
How long does it take to calculate 100 million by mouth?
How high are 100 million coins stacked together?
How long does it take to walk 100 million meters (by car or by plane)?
How many drops of blood are there in 100 million red blood cells?
How much is a hundred million drops of water?
How many trees do you need to cut down for 100 million pairs of disposable chopsticks?
3. Make an activity plan.
(1) activity steps.
(2) Activity preparation and division of labor arrangement.
And fill in the activity steps, activity preparation and division of labor in the activity record form.
Stage 2: Hands-on Practice
Each group carries out activities as planned, and records the obtained data and calculation process in the record form. Teachers participate in student activities with targeted guidance and help.
The third stage: draw a conclusion
Students describe the scale of 100 million according to the analysis of information and data and the specific situation.
The fourth stage: expression and communication
1. Each group states the whole activity process.
2. Summary of activities.
Imagine further how big 1 100 million is.
The activity process of the evaluation team.