Textbook analysis
This lesson is the beginning of this unit. It is a teaching content that combines concepts, measurement and calculation to study space and graphics. It is based on students' initial understanding of plane figures such as triangles, parallelograms, rectangles and squares. It is the basis for students to learn the calculation of perimeter of various figures in the future, and it is also an important basis for geometric knowledge.
Teaching objectives
(1) Knowledge and skills: Understand the meaning of perimeter through observation and operation, and measure and calculate the perimeter of some plane figures.
(2) Mathematical thinking: Through the process of observation, measurement and other mathematical activities, students can develop the concept of space while gaining intuitive experience and infiltrate the mathematical thought of "turning joy into straightness".
(3) Problem solving: In learning activities, different methods can be used to solve problems.
(4) Emotional attitude: Feel the close connection between mathematics and life, experience the success after overcoming difficulties with classmates, and establish confidence in mastering mathematics knowledge.
Important and difficult
Because the third-grade students are still in the transition stage from concrete image thinking to abstract logical thinking, and the content of this lesson is from the surface to the sideline, which is difficult to learn and understand, so,
Understanding the perimeter and calculating the perimeter of basic graphics are the teaching focus of this course; It is difficult to understand the meaning of perimeter and explore the measurement and calculation methods of various graphic perimeters.
Teaching methods of speaking and learning.
In order to let students master knowledge in the process of "doing mathematics", I comprehensively use the methods of "activity teaching method", "intuitive teaching method" and "classroom discussion method" to teach. "Hands-on practice, independent exploration and cooperative communication are important ways for students to learn mathematics".
Studying law mainly embodies the following two characteristics:
1. The teaching process embodies "two aspects, three actions and one participation": that is, let the whole class speak, use their brains, do their hands and participate in the whole process of knowledge generation, development and formation. ,
2. It embodies "let different people get different development in mathematics".
Teaching program design
The new curriculum standard points out: "Effective mathematics learning activities cannot rely solely on imitation and memory, but hands-on operation, independent exploration and cooperative communication are important ways for students to learn mathematics". In order to embody this new concept, I have designed four links to teach this course, namely, "creating an environment to stimulate interest, introducing new lessons-operating inquiry, building new knowledge-applying knowledge, deepening understanding-class summary, expanding and extending".
(A) set up the environment, stimulate interest and introduce new courses.
Activity 1: Have a look and compare.
Taking advantage of the opportunity of the 2008 Olympic Games, at the beginning of the class, I used courseware to create a concrete and vivid situation for the students: "Students, the 2008 Olympic Games is held in China, and animals are also actively taking part in physical exercise. Look, an ant is practicing running.
Vivid and interesting pictures immediately aroused students' interest in learning and thirst for knowledge. I took the opportunity to guide the students to observe and tell them what the ant ran along the leaves: guide them to find that starting from the starting point, walking along the edge of the leaves, and then returning to the starting point is a week of running the leaves. Through observation and comparison, let the students understand the meaning of "leaves of a week", so as to initially establish the appearance of perimeter and make necessary preparations for learning what is perimeter below.
(B) operational inquiry, building new knowledge
In this session, I mainly designed two activities.
Activity 1: Draw and say.
"Now, children, would you please choose a leaf from the collection and draw its circumference on the paper with a pen?"
After the students' independent activities, I asked the students to show their works and talk about "how to draw". The starting point of students' painting may be different. At this time, the teacher focuses on guiding students to make it clear that no matter where they start painting, they must finally return to the starting point. Thus, the meaning of "perimeter is the length of a closed figure" is permeated. The teacher summed it up and wrote it on the blackboard: the length of a leaf is its circumference.
Then ask the students to draw this picture in the first exercise after class.
After the students have experienced the above activities, let them understand "what is perimeter" in activities such as watching, drawing and speaking, so as to establish a descriptive concept of the perimeter of plane graphics. Through just a few minutes of painting, the students' experience is deepening. I think no amount of languages can replace this way of learning by doing. After students have a preliminary understanding of the meaning of perimeter, in order to make students understand "what is perimeter" more comprehensively and deeply, and feel the close connection between perimeter and real life. Let them find an object from their lives, or find a figure they like and say "What is the perimeter", for example, the length of a week on the cover of a math book is the perimeter of the cover of a math book; The length of a week on the desk is the circumference of the desk; Touch them with your hands, so that students can really feel the existence of the perimeter. The research of understanding conceptual psychology shows that the closer the learning content is to the familiar life scene of students, the higher the students' conscious acceptance of knowledge, so that students feel that mathematics is everywhere and have a strong interest in learning. From the perimeter of an object surface to the perimeter of an irregular figure, there is naturally a summary of the concept of "perimeter", followed by the teacher's blackboard writing: the length of a closed figure is the perimeter of the figure.
In order to cultivate students' hands-on operation ability and awareness of cooperation and communication. We can also let them know that not only we have girth around us, but also we have girth around us, so as to guide students to know waist circumference and head circumference.
"There are three kinds of pants in the store. Teacher Chen wants to buy a copy. How do I know what size I fit? " Guide the students to say that they should measure their waistlines. It is necessary to choose appropriate measuring tools and methods according to the actual problems in the measurement process, and carry out mathematical inquiry activities by measuring. So I let the students choose their own measuring tools and methods, and cooperate with each other to measure the waist circumference at the same table. At the same time, it also stimulated their interest in learning mathematics. As the saying goes, it is better to watch it ten times than to do it ten times. Only in the process of hands-on operation can we cultivate students' innovative consciousness and practical ability.
(C) the use of knowledge to deepen understanding
Create a "breakthrough" situation to stimulate students to devote themselves to the later study with greater enthusiasm. If you don't pass a level, you will get the corresponding score, and the winner who scored the most in the end is today. "
Level 1: Measure and calculate the perimeter of the figure below.
Ask the students to choose the appropriate measuring tools and use the appropriate methods to measure the perimeter of these figures in cooperation with the students in the group. "
Let students learn the method of measuring the perimeter of plane figures in group inquiry, which paves the way for the subsequent study of the calculation method of the perimeter of geometric figures, and also takes care of students at all levels, which embodies the mathematical concept of "everyone learns valuable mathematics". )
The farmer's uncle wants to build a fence around the garden. How long is this fence?
"Mathematics Curriculum Standard" points out; The important purpose of learning mathematics is to use mathematical knowledge to solve practical problems in daily life, so that students can experience the process of abstracting practical problems into mathematical models and explaining and applying them. Therefore, the design of math exercises must be close to the real life that students are familiar with, so I designed the above two exercises.
The third level: in order to let students feel the mathematical thinking of translation, cultivate the ability to use knowledge flexibly, and let students judge whether the perimeters of the two figures in each small question are the same? Teachers guide students to observe the numbers, make their own judgments first, and then discuss in groups. When speaking in class, the teacher uses multimedia to show the process of sideline movement, so that students can intuitively see that the perimeters of the two figures in the first group are different, and the perimeters of the two figures in the second question are the same.
The whole game is from easy to difficult, which conforms to the psychological characteristics and knowledge and experience level of junior three students. This design can make students realize that there is mathematics everywhere in life, and mathematics is around them, which greatly arouses students' sense of participation and enables students to learn, master and apply knowledge in a relaxed and pleasant atmosphere. Freiland Tal, a Dutch scholar, pointed out: "The best way to learn mathematics is to learn by doing". "I think it's an armchair strategist. I don't know if it must be done."
(D) class summary, expansion and extension
1, class summary: In order to summarize the knowledge, skills and thinking methods learned in this section, I designed the following questions to guide students to make class summary: ① What have you gained from this class? ② What else do you want to know about the circumference? 2. Extension: Find a favorite leaf after class and measure its circumference. Design intention: This kind of expansion from in-class to out-of-class not only enriches the content of teaching materials, but also extends students' interest in learning infinitely.
blackboard-writing design
My blackboard writing revolves around the topic of "what is perimeter", starting with leaves and a figure, and then guiding students to choose objects or specific figures in life and say "what is perimeter". This will deepen students' understanding of "what is a circle" from individual to general, thus realizing the teaching objectives of this course in a down-to-earth manner.