Knowledge points of mathematics "measurement" in the first volume of the third grade of a primary school
1. In daily life, relatively few items can be measured in millimeters (mm), centimeters (cm) and decimeters (dm). Large objects are usually measured in meters (m).
The relatively long distance is generally in kilometers.
2. The track of a sports ground is generally 400 meters 1 lap, and 1000 meters is 2 and a half laps.
3. 1 The thickness of coins, rulers, magnetic cards, buttons, keys and ID cards 1 min is about1mm. ..
4. When the length or required quantity of an object with a relatively short volume is relatively accurate, it can be measured in millimeters.
5. The length of each cell in the middle of1cm is1mm.
6. When calculating the length, you can only add or subtract the same length unit; When the units are different, they should be converted into the same units before calculation.
7. When expressing the weight of an object, mass units are usually used. The weight of lighter items can be measured in grams. According to the quality of general commodities, it is often taken as "kilogram"; Generally, "ton" is used to represent the mass or carrying mass of large objects.
8. Common length units: meter, decimeter, centimeter, millimeter and kilometer.
9. Length units: meters, decimeters, centimeters and millimeters, and the forward speed between every two adjacent units is 10.
1 m = 10 decimeter, 1 decimeter = 1 0cm,1cm =10mm.
1 m = 100 cm
1 km (km) =1000m
10, mass unit: tons, kilograms and grams, and the forward speed between every two adjacent units is 1000.
1 ton = 1000 kg
The teaching plan of "Measurement" in the first volume of mathematics in the second elementary school and the third grade.
In the second grade, students got to know the length units "centimeter" and "meter" and the mass units "gram" and "kilogram", which is the first stage of understanding measurement. In this unit, students will further learn the unit of length "millimeter", "decimeter", "kilometer" and "ton", which is the second stage of understanding measurement, laying a foundation for further study of area, volume, unit of volume and its measurement. Through the study of this unit, students will have a systematic and complete understanding of commonly used length units and quality units. (1) Pay attention to students' knowledge and life experience and experience the formation process of new knowledge.
1, make use of students' knowledge and experience to innovate.
Before that, students have learned the meters and centimeters in length units and the kilograms and grams in mass units, and learned some knowledge and methods about measurement. Therefore, when learning the content of "understanding of millimeters", we should have an understanding of centimeters as the basis. The textbook arranges activities for students to evaluate, test and discuss, reflect the formation process of knowledge, and lead to new knowledge to learn. When teaching the relationship between length units and quality units, we should fully guide students to communicate, talk about progress and methods, and use existing knowledge and experience to calculate, so as to master the correct thinking method.
2. Use students' life experience to stimulate interest.
In real life, students are familiar with the length units of millimeters, decimeters and kilometers and the mass units of tons, and have accumulated some life experience. The compilation of teaching materials has also fully considered this point, and designed classrooms, playgrounds, campuses and other familiar environments for students to integrate the concepts they have learned, let students discover, explore and experience, and stimulate their interest in inquiry. In teaching, teachers should make full use of students' life experience, let students experience the formation process of new knowledge, and deepen the breadth and depth of exploration.
(2) Pay attention to the operation and experience in practical activities, understand the unit of length and establish the concept of length.
1, understand the "millimeter" in the operation.
First of all, I feel the necessity of making millimeter in hands-on operation, understand the meaning of millimeter, and initially establish the representation of1mm. Secondly, let students use gestures to indicate the length of 1mm to enhance their perceptual knowledge. Finally, tell the students which objects are 1mm in length, inspire them to list more familiar things, and further enrich their perception of 1mm or several millimeters.
2. Understand decimeter in comparison.
First of all, when teaching "understanding decimeter", we should pay attention to the comparison of decimeter, centimeter and meter. Understand the length of 10 cm through the introduction of the meter ruler, and directly introduce to students that 10 cm is 1 decimeter, thus establishing the representation of decimeter. Secondly, by using different gestures to express the length of 1 decimeter, the intuitive understanding of decimeter is strengthened. Finally, let the students think about "How many decimeters is 1 meter" and further establish the concept of decimeter length in comparison.
3. Perceive "kilometers" in experience
Because "kilometer" is a relatively large unit of length, it is not easy for students to directly perceive it, so we can understand the textbook by strengthening experience and reasoning with the help of what students are familiar with. For example, when you know the number of kilometers, choose the playground runway that students are familiar with to lead in 1 kilometer. In teaching, teachers can let students know according to the actual situation of the school, such as "200-meter runway, 5 laps is1km; 400 meters runway, two and a half laps is 1 km. "In order to enrich students' experience, arrange students to actually walk 100 meters, and feel that the length of 100 meters is 1 km. At the same time, under the premise of ensuring students' safety, students can also walk the length of 1 km, and enhance their feelings about the linear distance of 1 km.
(3) Pay attention to creating realistic situations and understanding high-quality units.
This unit's understanding of the quality unit ton is abstract, not as intuitive and concrete as the length unit, so it is difficult for students to directly contact and feel it in life. Therefore, the teaching materials provide intuitive and vivid teaching materials. In teaching, teachers can fully create realistic situations that students are familiar with, thus mobilizing students' enthusiasm and improving students' participation in the teaching process. For example, guide students to observe the scene of containers and freight trains carrying bulk goods and feel the wide application of "tons" in life; With the help of common materials such as rice and the weight of primary school students, students can understand the weight of 1 ton through reasoning. At the same time, make use of the situation closely related to life in Do One Thing to enrich students' perceptual knowledge of tons.
(D) Strengthen students' mastery of estimation methods and cultivate students' estimation consciousness and ability.
The textbook attaches great importance to cultivating students' estimation ability. Examples are specially arranged for this purpose, and a large number of estimation activities are provided in the exercise. Teachers should pay attention to cultivating students' consciousness of consciously estimating the length or mass of objects, and at the same time pay attention to guiding the estimation methods. First of all, students are encouraged to sum up the estimation methods with their own experience and experience the diversity of estimation methods in communication. For example, teach "estimate how far it is from home to school." Sometimes, in addition to walking and going to school by bus as mentioned in the textbook, parents are also asked to talk about their thoughts on children riding bicycles or driving. Secondly, according to different situations and students' experience, the estimation methods are guided to improve students' estimation ability. Finally, the method of estimating first and then measuring and verifying can be adopted to further cultivate students' estimation consciousness and ability.
(5) Pay attention to the process of solving problems and feel the way of thinking listed one by one.
Reflections on the teaching of "Measurement", the first volume of mathematics in the third grade of primary school
Students don't know how to measure in their minds, so they learn millimeters and decimeters on the basis of understanding length units and centimeters first. In teaching, I arranged some activities for students to measure. For example, measure how long the short side of a math textbook is, how long the rubber difference is, and how long the line segment is, so that students can experience the actual lengths of 1 cm and 1 mm in activities, and at the same time express the actual lengths of 1 cm, 1 m and 1 decimeter with gestures respectively, so that students can perceive the actual lengths in their minds. Then use an ID card with a thickness less than 1 cm for students to measure. The results show that the length unit is smaller than cm by millimeters, and students think that 1 mm is about the thickness of a bank card. After students know 1mm on the ruler, they can measure shorter objects that are not whole centimeters. Next, I arranged a piece of hard paper with a length of 10 cm, so that students could estimate before measuring, which led to the concept of "1 decimeter". Knowing "1 decimeter", I organized students to carry out the activity of "looking for it" to see who could find the objects around "1 millimeter" and "1 decimeter". The children's enthusiasm for learning has suddenly improved. I asked them to discuss in groups and choose representatives to speak. The answers vary. Some say that the thickness of ID cards, coins and magnetic cards is about 1mm, and another child says that the thickness of 10 paper is also about 1mm, which makes students think. In this class, I give full play to the learning position of students' hands-on operation, guide students to re-estimate and measure, and organize students to measure the length of paper, needle and thread and the objects around them, such as ballpoint pens, pencils, pencil boxes, chalk and desks. Make students establish the concept of 1 decimeter, 1 millimeter, 1 meter and 1 cm in their brains. Lay a solid foundation for the future. Of course, there are also many shortcomings. For example, students do not have a good grasp of the relationship between decimeter, centimeter and millimeter. Secondly, they can't measure with a ruler. Thirdly, the measurement method is inflexible. All these need to be improved in future teaching.