Knowledge points of "ton understanding" in mathematics of the third grade in the first primary school
Meaning: measure the mass of heavy goods or bulk goods, usually in tons, represented by the symbol T.
For example, 1 bag of rice weighs about 10 kg, 100 bag of rice weighs about 1000 kg, which is 1 ton.
Unit conversion:
1 ton = 1000 kg
2 tons =2000 kg
Methodological analysis:
1 ton = 1000 kg, 2 tons is two 1 ton, that is, two 1000 kg, that is, 2 tons =2000 kg.
Methods induction:
When converting a larger mass unit into an adjacent smaller mass unit, three zeros are added at the end of the converted number, and when converting a smaller mass unit into an adjacent larger mass unit, three zeros are deleted at the end of the converted number.
The application of tons in life;
A large number of understanding teaching plans for mathematics in the second and third grades of primary school
Learning situation and teaching material analysis: "Understanding Tons" is a common concept teaching course, and it is also the teaching of a large measurement unit. Generally speaking, students seldom come into contact with large measurement units, and it is difficult to establish their own ideas, which is the difficulty in the teaching of measurement units.
Teaching objectives:
1, so that students can know the unit weight of tons, know the practical application of tons, initially establish the concept of 1 ton, and know that 1 ton = 1000 kg.
2. Simple conversion between quality units can be carried out.
3. By observing, comparing and guessing, cultivating students' awareness and ability to estimate the quality of objects can solve some related problems in real life.
Emphasis and difficulty in teaching:
1. key point: establish the concept of "ton" as the quality unit and the conversion between ton and kilogram.
2. Difficulties: Establish the concept of "ton".
Teaching preparation:
Ask the students to weigh themselves before class.
Teaching process:
First, create situations and introduce new lessons.
1, guess the teacher's weight.
The teacher asked the students to guess the teacher's weight. After guessing, the teacher asked: Just now, all the students used the same unit of mass-kilogram. Why not use "gram" as the unit?
2. Teacher: Do you know the weight of any animal in the world? What is its approximate weight? The courseware shows the introduction and related information of the blue whale. )
Teacher: The quality of blue whales should be measured in tons. Today we are going to know this new quality unit (blackboard writing: understanding of tons). Can you give an example of an object in tons in life?
3. The teacher's courseware shows some objects and their corresponding masses in tons.
The teacher asked: What are the characteristics of objects in tons?
The teacher pointed out that the ton is a unit of mass larger than the kilogram. Measure the weight of heavier or larger items, usually in tons. Tons can be represented by the symbol "t".
Design intention: By guessing the teacher's weight and the blue whale, an animal with world weight, let the students feel that ton is a big unit of measurement, and establish the concept of ton by giving students examples and showing the teacher's pictures. 〕
Second, cooperation and exchanges, independent exploration.
1, a preliminary understanding of tons.
The teacher uses courseware to show the theme map of 1 1 page.
Teacher: Who do you think is here? It was a sunny day. Bear, pony, calf and deer meet and play by the river. When they came to a small bridge, the pony suggested, "There is a bridge here. Let's cross together. " The bear said, "Wait, there is a sign here that says' weight limit 1 ton'!"
The teacher inspired the students to think: What does the weight limit of 1 ton mean? 1 ton? What is the relationship between "tons" and "kilograms"? Can four small animals cross the bridge at the same time?
Teacher: Who knows how many kilograms 1 ton equals?
Students can say from their life experience: 1 ton = 1000 kg.
Teacher: Can these four animals cross the bridge at the same time?
[Academic presupposition: Because students know 1 ton = 1000 kg, they will probably think of adding up several figures to try. Then the teacher can ask further open questions: how do they cross the bridge? Inspire students to think: they can pass one by one; You can also go through two at a time, or you can … cultivate students' cooperative spirit and solve problems in different ways through students' exchanges and supplements. 〕
Can you cross the bridge at the same time? Ask the students to add up the weight of the animals and compare it with 1 ton.
400+300+500+100 =1300 (kg)
1300 kg is heavier than 1000 kg, that is, it is heavier than 1 ton, so we can draw a conclusion.
2, fully feel the ton.
(1) Students carry 25 kilograms of rice per bag, which feels like 1 ton.
Students are divided into groups. Everyone holds a bag of rice and feels the weight of 25 kilograms of rice. Students with little strength can also carry it by two people.
The students reported their feelings after the operation.
Calculate for yourself: 1 bag of rice weighs 25 kg, 1 ton of rice. How many bags are there? (40 bags)
With the help of multimedia demonstration, the teacher presents four bags of rice at a time (because the four bags are 100 kg), and the number of students watching them is 100 kg, 200 kg, 300 kg, 400 kg ... 1000 kg. When 40 bags of rice fill the whole screen, students will sigh: Wow! 1 ton is so heavy!
(2) Feel again 1 ton.
Teacher: Before class, you all weighed yourself. How many kilograms do you weigh? Back each other again and feel the weight of 1 student. Finally, calculate or estimate the number of children at the same table with this weight, which is 1 ton.
3. For example, ask students to talk about what weighs about 1 ton in life.
Teachers can use courseware to show examples in textbooks. They can say, "If each student weighs 25 kilograms, then the weight of 40 students is 1 ton." It can also be said that "two cows weigh about 1 ton." It can also be said that "two horses 1 bear add up to about 1 ton." ..... more students should tell examples in life. (For example, the load capacity of an ordinary elevator is 1 ton)
4. Conversion between tons and kilograms
The example given by the teacher is 7:3 tons = () kg.
6000 kg = () tons
This part of the content is not difficult for students. You can let the students fill it out independently first, and then let the students communicate in the group, and the class can explain the method collectively.
Design intention: Progressive learning is relatively simple for students, and the teaching method of allowing students to think independently and then give feedback is adopted to give full play to students' enthusiasm and initiative in learning.
5. Students independently complete the topic "Doing" on page 12 of the textbook.
(1) What are the projects in tons?
(2) Is it overloaded to load six 300kg machines on a 2-ton truck?
[Design intention: Practice while speaking, and the combination of speaking and practicing will help students consolidate their knowledge in time. ]
Third, consolidate practice, expand and improve.
1. Students independently complete exercise 3 1 and 2 in the textbook.
The problem 1 is a set of interrelated problems. Through the practice of this problem, students' feelings about the quality unit ton are further deepened. You can use the method of independent connection first and then communication.
Question 2: Let the students practice independently first, and then let the students talk about their ideas collectively.
2. Exercise 3, question 3.
The answer to this question is not unique. As long as each car does not exceed 2000 kilograms of machinery, that is, 2 tons. Because students consider different angles and load different ways, let students express different opinions.
3. Error correction (math diary of Xiaoming).
Today is Sunday. I ate two 100 Jin meat buns in the morning, and then I went to the market to buy food with my mother.
There are so many goods on the market! I can't see clearly. My mother and I formed a big circle. We bought 1 g coriander, 2 tons of tomatoes, 3 kg of eggs, 1 kg of cabbage and 500 kg of meat. My mother and I sweated with these things.
Fourth, class summary.
What did we learn today? What did you get?
Verb (abbreviation of verb) expansion homework
Reflections on the Teaching of Mathematics Understanding in Grade Three of the Third Primary School
Before learning the unit of mass of tons, students have had a perceptual understanding of grams and kilograms. I see. 1 kg = 1000 g. The mass of light objects is often measured in kilograms, while that of ordinary objects is measured in kilograms. In this way, students know that tons are often used as units when measuring heavy objects or large objects. But how much does a ton weigh? Students have no intuitive understanding. It is also impossible for students to establish perceptual knowledge by weighing a 2-cent coin or two bags of salt like grams and kilograms. Therefore, it is really difficult to establish a concept by taking tons as a unit of mass. In this lesson, in the process of creating problem situations, I ask students to use their tons of knowledge to solve the load of small animals crossing bridges, trucks and elevators, how many objects weigh about 1 ton, and which objects should be measured in tons, so as to estimate the mass of some large animals, so that students can experience tons of knowledge at hand. Learning tons of knowledge can solve many practical problems in life. Let students experience that mathematics comes from life and is used in life to stimulate students' interest in learning mathematics. In order to break through the difficulty of this class, I first use 10 bag 100 kg of rice in class, and the mass is 1 ton, so that students can feel the weight of 1 ton. Re-use the weight of the children in the class to experience quantitatively. I found a classmate in my class who weighs exactly 25 kilograms. Let the students imagine that about 40 students weigh 1 ton. Then tell the child that my weight is 50 kilograms. The weight of 20 teachers is 1 ton, and the textbook also stipulates that the weight of two cows is about 1 ton. Let the students feel 1 ton in the comparison figures.
However, in teaching, it is found that the calculation ability of junior three students is still poor, and it is difficult for students to calculate how many objects weigh about 1 ton. Whether there is a larger and more direct object that can help students build the performance of 1 ton; Although students are allowed to have a complete experience, they are third-year students and are separated from them. Life is so far away that some students don't know the mass of kilograms and grams, so it's a bit outrageous to estimate the mass of objects by tons. A student said that the weight of a tree in a teaching building is about 1 ton. When teaching, students should be compared with 1 ton, such as 2 cows and 40 classmates. Because tons are used to measure the mass of large objects, students seldom make mistakes in doing problems. But in fact, students are not very good at mastering this unit.