Teaching plan and teaching reflection of "How big is 100 million" in the first volume of fourth grade mathematics published by People's Education Press.

How big is the teaching design of 100 million?

Teaching content: How big is 100 million? The Protestant textbook of People's Education Press Unit 1, Volume 7, Mathematics of Grade Four in Primary School.

Teaching material analysis:

Textbooks attach great importance to the cultivation of number sense in the concept teaching of number. Let the students understand the meaning of numbers and establish their digital consciousness through their perception and experience of specific numbers. However, because the number 1 100 million is too large, it is difficult for students to get an intuitive feeling by combining specific quantities. Therefore, after the "understanding of large numbers" unit, this comprehensive application is arranged, so that students can experience the process of guessing, experimenting, reasoning and comparing through inquiry activities, and fully feel the number of 654.38 billion by using imaginary materials.

Teaching objectives:

1. Through the practical activities of "weighing", "counting" and "arranging", students can feel the size of 100 million from different angles, and can express their feelings about the size of 100 million with concrete things in combination with reality.

2. Cultivate students' interest in learning mathematics and their ability to solve practical problems, and enhance their awareness of active participation and willingness to cooperate in activities, so as to cultivate excellent morality of diligence and thrift.

Teaching philosophy:

Mathematics teaching is based on students' existing knowledge. Teachers should teach students to acquire new knowledge with the help of existing knowledge and cultivate students to dare to learn independently and try new knowledge. Primary school students' existing mathematical cognitive structure and life experience provide the possibility for them to solve mathematical problems independently. For this reason, when I teach "knowledge of extensibility and migration", I directly let students try and explore independently, guide students to think independently, give students space and time to explore new knowledge independently through operation, observation, analysis, comparison, reasoning, discovery and summary, create opportunities for students to participate actively, and let students develop in exploration.

Teaching emphases and difficulties:

Key points: Perceiving the size of 100 million difficulties: Cultivating students' sense of numbers.

Teaching process:

First, the dialogue reveals the topic.

Students, do you know how many people there are in China? So do you know how big 100 million is? Secret topic: How big is 100 million?

Write 1000000 and 1 100 million on the blackboard. Then guide students to understand the size of 65.438+billion from the composition of numbers: 65.438+billion, 65.438+billion, 65.438+billion, 65.438+billion and 65.438+billion. ...

Who can say how the number "100000000" makes you feel? (particularly large)

Two. Actual operation

(1) weighing.

So how big is 10000000? Do you want to really feel it? The following teacher will tell you a story:

In ancient times, there was a minister named Liu En, who was very concerned about the sufferings of ordinary people. Once the Yellow River flooded again, and the choppy Yellow River washed away many houses, leaving thousands of people homeless. After learning about the disaster, Liu En was very anxious and immediately wrote a letter to the emperor at the fastest speed. After reading Liu En's memorial, the emperor ordered him to go to the disaster area for disaster relief. After Liu En arrived in the disaster area, he immediately started disaster relief work. He lived with the people, sharing weal and woe, and finally let them rebuild their homes and live a happy life. The people in the disaster area were very grateful to Liu En, and every household hung a portrait of Liu En, but the emperor was very jealous when he learned about it. He didn't want to reward Liu En, but he thought of a good way for fear that others would gossip about him. One day, he called Liu En and praised his contribution to disaster relief. Then he said to Liu En, "Food is the most important thing for the people. You have saved so many people in the disaster area, and I will give you an extra 1 million grains of rice every month. " As soon as the emperor had finished speaking, other ministers laughed and thought, is this the emperor's reward for Liu En? Only 10000000 grains of rice is a little bit. But Liu En was very happy and thanked the emperor. Do you know why Liu En thanked the emperor happily?

Can you guess the weight of 1 100 million meters

(Let the students guess)

Is there any good way for us to weigh 1 100 million meters skillfully?

(Students discuss)

The teacher put forward the design scheme.

Weight 1 100 million grains of rice.

1, first weigh 100 grain of rice, then divide it by 100, then calculate the weight of 1 grain of rice, and finally multiply it by 1 billion to calculate the weight of 1 billion grain of rice. (or calculated according to the ratio relationship)

2. First weigh 10g rice, then divide it by the number of grains of rice, and finally multiply it by 1 billion to calculate the weight of 1 billion grains of rice.

3. Teacher's request: Choose a scheme and calculate the quality of 654.38 billion grains of rice in groups of four. Please write out the calculation process to facilitate the later report, and you can use a calculator to help with the calculation.

4, student group calculation

5, each group reported the results, the teacher wrote on the blackboard, feeling the number of 65.438+0 billion grains of rice.

From the activity just now, we know that 654.38 billion grains of rice weigh about 2.5 million grams, while the population of China is 654.38 billion. If everyone saves 654.38+0 grains of rice every day, how many grams of rice can the whole country save every day? If everyone eats 400 grams of rice every day, how many days can one person eat these saved rice? About how many years?

(student computing)

How do you feel after knowing this information?

(Educate students to cherish food)

As we all know, this year, General Secretary Hu Jintao put forward the idea of "building a conservation-oriented society with Scientific Outlook on Development". Do you know why General Secretary Hu put forward the idea of building a conservation-oriented society in Scientific Outlook on Development?

Although there are many people in our country, it is harmful to have many people, and production and life consume a lot of energy.

2. Count.

(1) Group activity, start counting.

Group, each person takes some exercise books, mix them together, and count them one by one. When the number of people reaches 100, the teacher immediately tells each group the time spent, and the team leader records it. Time spent on communication between groups after completion.

(2) Work in groups and ask questions.

Dialogue: At this rate, how many seconds do we need for hundreds of millions of exercise books?

Show the form in the book (90 seconds can be changed into seconds recognized by the whole class), and let the students calculate in groups and fill in the results.

Feedback, say the number of readings.

(3) Further exploration.

Dialogue: 90 million seconds. Is that a long time? It is obviously inappropriate to express such a long time in seconds. What kind of time unit do you think should be adopted? How to convert (year) into how many years? After the students say the method, read the formula in the book.

The students worked out the result with calculators. Question: What do you think of this result?

Step 2 line up.

Talk: Just now we felt the size of time 100 million by counting. Do you want to feel the scale of 100 million again in other ways?

(1) Actual measured length.

Please 10 students stand in a row hand in hand, and the teacher and students measure the length together. (Take the whole meter)

(2) List calculation.

Question: According to this calculation, how long will it take for 100 million children to stand in a row hand in hand?

Show the form. According to the form, each group will also fill in the form according to the measurement data list just now and feed back the calculation results.

(3) Further perceive the size of 100 million from the circle number of the earth.

Read the calculated length by name.

Dialogue: For this length, everyone will think it is very long, but how long it may be is not deeply felt. The equator of the earth is 40 million meters long, 1 100 million children stand hand in hand in a row. How many times can the equator of the earth spare? Do the math with a calculator. If a student's calculator can only display eight digits, it is necessary to change meters into kilometers.

Name the calculation results.

Question: How do you feel after reading this data?

Third, raise awareness and sublimate emotions in activities.

Read the information below and say how you feel.

654.38 billion drops of water can be collected into about 3333 liters of water, which can hold four large water trucks.

1 100 million pieces of paper are stacked together, which is about 10000 meters high, which is higher than Mount Everest.

In recent years, China's wheat output has been stable at around 65438+ 100 million tons.

Xinmin Daily, February 26, 2004-The United Nations Food and Agriculture Organization announced on Wednesday that more than 6,543.8 billion chickens have been slaughtered in Asia where bird flu broke out.

In 200 1 year, the number of mobile phones in China has exceeded 1 100 million.

Verb (abbreviation of verb) Let's talk about it.

How big is 100 million in the group?

Fourth, the class summary

What did you learn from today's study? How do you feel?

5. Regarding 1 billion, what other issues do you want to study through today's study?

(Possible situations: the thickness of 65438+ billion pieces of paper, the thickness of 65438+ billion one-dollar coins, the mass of 65438+ billion people, the length of 65438+ billion seconds ...)

Can you write a design plan about the problem of 1 100 million you want to study?

The thickness of 100 million pieces of paper is higher than that of Mount Everest; /kloc-the weight of 0/100 million coins is more than four times that of three adult blue whales; 1 100 million grains of rice can fill the stomachs of 35,000 people; 100 million primary school students can walk hand in hand around the equator three and a half times; 1 100 million is a big number!

It takes 2500 trees to make disposable chopsticks every year! And these trees must be 50-60 years old! But these chopsticks are of little use, just for eating. It's useless after dinner! China produces and discards 45 billion pairs of disposable chopsticks every year! Because of this, birds have no home.

If a drop of water is wasted every second, 12 19200 drops will be wasted every month. More than 400 million drops of water will be lost every year! Because of this, fish have no home.

These are all caused by soil erosion, just because of those people who don't understand culture and didn't go to school as children. But you can't blame them. If they had the opportunity to learn, know how to protect the environment and know more knowledge, they wouldn't be like this!

What will human beings look like in the future? It must be improved by human environmental protection.

Come on! Come on! Let's protect the environment, let's improve it!