First, teaching materials and teaching objectives
1, teaching material analysis
The content of this lesson is arranged on the basis that students have mastered the characteristics of rectangles and squares and can calculate their perimeters. The outstanding change of "area" arrangement is to strengthen exploration and let students experience the formation process of knowledge. The textbook first makes students understand the necessity of introducing area units, and designs a series of "contradictions and conflicts": two rectangles with similar areas but different shapes, it is difficult to see which one is bigger by observation, and it is difficult to compare their sizes by overlapping. Therefore, students have cognitive conflicts, prompting them to try to use indirect comparison method, that is, to compare with other graphics as the standard. Through personal experience and discussion, the students found that "to compare the sizes of two figures, they should be measured in a unified area unit". Then the textbook further inspires students to explore "what kind of graphics are suitable for representing area units", so that students can find that "square measurement is more convenient" through independent exploration, and then naturally lead to the teaching of area units. The focus of this lesson is to understand the meaning of area and know the unit of area. The difficulty lies in: initially establishing the representations of 1 cm2, 1 decimeter square and 1 square meter, so that students can realize the necessity of unifying area units.
2. Teaching objectives
The teaching objectives of this lesson are as follows:
(1) Understand the meaning of area.
(2) Understand the commonly used area units: square centimeter, square decimeter and square meter, and initially form the spatial concept of the actual size of these units and form a correct representation.
(3) Learn to compare areas by observing, overlapping and estimating.
3. Analysis of learning situation
Grade three students are in a critical period of learning ability development, and their concrete image thinking is also transitioning to abstract logical thinking. Based on students' own spatial perception, I arrange a lot of observation, comparison, measurement, operation and other activities in teaching, so that students can experience the transition from concrete to abstract in practical activities and truly implement the goal of cultivating and developing spatial concepts.
4. Time schedule
Based on the above understanding of the textbook and according to the requirements of the syllabus, this lesson is taught from the following aspects:
(1) Let students understand the meaning of area by pointing, touching and comparing activities. It takes five minutes.
(2) In the process of solving problems, let students feel the necessity of establishing area units and get a preliminary understanding of the law of establishing area units. It takes 10 minutes.
(3) Know the common area units: square centimeter, square decimeter and square meter, and get the spatial concept about their actual size in the activity, and form a correct representation. It takes 15 minutes.
(4) Cultivate students' observation ability, operation ability and summary ability, so that students can realize that mathematics comes from life and serves life. It takes 10 minutes.
5. Prepare teaching AIDS and learning tools
Teaching aid: multimedia courseware. There are 1 cm2, 1 cm2, 1 m2. Two rectangles of different sizes.
Learning tool: two rectangles with similar area but different shapes. Square and rectangular pieces of paper with different sizes and objects with 1 cm2 and 1 cm2.
Second, teaching methods and learning methods.
The teaching methods I use in this class are observation and experimental inquiry, and scene introduction and intuitive demonstration run through all teaching links. For example, at the beginning of the class, through the introduction of the situation, a colored competition situation is created to improve students' interest in learning and the need to explore new knowledge. In order to understand the meaning of area, I let students truly feel what area is through intuitive demonstration and hands-on activities, and get real direct experience in using learning tools, hands-on operation and cooperative exploration. In order to let students form a correct representation of the actual size of the area unit, I adopted the activity teaching method. The purpose is to create mathematical situations, put forward mathematical problems, let students experience learning in activities, establish correct representations, and use these representations to solve related problems. After students understand the appearance of the area and the establishment of the area unit, I give students the right to explore and guide them to study by themselves with questions. Through self-study, students can quickly understand the meaning of area units and learn to compare the size of areas through observation, superposition and estimation.
Third, teaching procedures and teaching strategies
According to the characteristics of teaching materials and students, I teach from the following links to cultivate students' three-dimensional goals.
1, stimulate interest and introduce new courses.
According to the age characteristics of grade three students, on-site study is easy to arouse interest, so I will introduce it with two pieces of white paper of different sizes. When the students finished, I asked this question: Who lost? Who won? What is the reason? Let students truly realize that planes are surfaces of different sizes, paving the way for students to learn the concept of area.
This link has two purposes: first, let students experience and feel in the participation of the game, and naturally lead to new knowledge on the basis of students' answers, paving the way for the study of new knowledge; The second is to stimulate students' interest in learning and arouse their desire for further exploration.
2. Fully perceive and summarize the meaning of area. This link is completed in three steps.
Step 1: Teach the surface perceived area of an object.
Ask the students to point out the surface of the objects around them (such as blackboard, table, book, etc.). ); What it feels like to touch the surface of these objects; Compare the surfaces of these objects, and let the students perceive the surfaces of the objects through them. On this basis, it is concluded that the size of the surface of objects is their area.
Step 2: Teach the size of closed graphics.
By asking questions: suppose we draw the cover of the exercise book on the blackboard. What shape is it? Draw closed figures and show a group of closed figures, so that students can recognize which ones are closed figures. Point to the area of closed figures and compare them with other closed figures, so that students can feel that the size of closed figures is also called their area.
Step 3: Summarize the meaning of area.
Students sum up the meaning of area, and the teacher writes on the blackboard: the size of an object's surface or closed figure is their area.
The design of this link is realized through students' personal experience and interaction with the environment. What is "noodles"? I don't know, I don't know. But in a large number of intuitive, practical and experiential activities, students can really feel what "noodles" are.
3. Through observation and comparison, let students understand the necessity of unifying area units.
There are large and small areas, how to compare their sizes?
(1) courseware shows: two rectangles with similar area but different shapes. Let the students think: What method can be used to compare which area is smaller? Students can't compare directly through observation and overlapping, which causes students' cognitive conflict and urges students to try indirect comparison, that is, to compare with other graphics.
(2) Provide learning tools for students to choose their own measurement standards for comparison.
(3) presentation. Students choose different criteria in the process of selection: some choose different shapes and sizes of graphics, that is, rectangles and squares are mixed together to swing; Some choose graphics with the same size (such as squares or rectangles), so that students can find through personal experience that as standard graphics with different shapes and sizes, they can't get consistent measurement results, so that "to compare the sizes of two graphics, we must use a unified area unit to measure". Let the students think further, what kind of figure is suitable to represent the area unit? Because the students in front have already put it together and measured it, the students naturally chose the square.
In this link, I mainly adopt the learning methods of hands-on, independent inquiry and cooperative communication, and provide learning tools, guiding operation and cooperative inquiry after stimulating cognitive conflicts. Giving full play to the main role of students' learning embodies the active mathematics learning process and effectively improves the efficiency and quality of classroom teaching.
4. Know the commonly used area units. This link is completed in three steps.
Step 1: Let the students teach themselves the textbook and show the corresponding self-study tips.
Step 2: Learn three commonly used area units of different levels. The teaching of learning "1 cm2" is mainly based on "teaching", and the specific links are as follows: Take, let the students take out a square with an area of 1 cm2 from the learning tool; Yes, look at the figure with an area of 1 cm2 and print it out in your mind; Compare, compare which nail area on your hand is about 1 cm2; Draw, draw a square with an area of 1 cm2; Measure, measure how many square centimeters is your eraser? The teaching of learning "1 square decimeter" is based on "help"; Learning "1 m2" is mainly based on "putting down". The above teaching methods encourage students to consolidate the area unit and develop the concept of space.
Step 3: Measure the surface area of an object with an area unit, and apply the learned knowledge to practice to solve problems and promote the combination of theory and practice. To this end, in teaching, we have carried out the operation exercises for students to measure the blackboard eraser, book cover and desk, so that students can learn to measure the area of blackboard and classroom floor.
In this link, I use the way of self-tutoring, so that students can teach themselves with questions, and then fully perceive the actual size of the area unit in newspaper, drawing, finding and measuring, and establish contact with a certain surface around them, thus helping to remember images.
5. Practice internalization and consolidate new knowledge.
In this session, I designed three exercises. The first topic is the need to strengthen the unified regional unit; The second question is to let students learn to distinguish length units from area units, pave the way for the next class, satisfy students' thirst for knowledge at different levels, embody the principle of teaching students in accordance with their aptitude, and provide students with space for creative thinking; The third question further deepens the representation of area units in students' minds.
(1).
The size of (1) () or () is called their area.
(2) A square with a side length of () and an area of ().
② Fill in the appropriate units.
The area of a stamp is about 4 square meters.
The floor of the classroom is about 45 square meters.
Xiao Ming's height is 125 ()
The length of a math textbook is about 20 ()
③ Spelling: Spell with a square of 1 cm2.
(1) Square and rectangle with an area of 16 cm2.
(2) Graphics with an area of 8 square centimeters.
6. Class summary
This link is mainly to let students talk about their gains, which not only exercises students' language expression ability, but also lets teachers know what students have learned in this class.
Fourth, teaching experience.
The teaching of this class fully embodies the "learning-oriented" teaching concept in the new curriculum standard, which has the following two outstanding characteristics:
1, based on the whole, pay attention to the students' main role, always put students' experience and exploration in the first place, and let students realize the teaching objectives of this lesson through a series of activities such as speaking, watching, touching, comparing and thinking under the guidance of teachers. Whether it is time arrangement or teaching strategy, it is combined with students to provide students with a lot of time and space for active exploration, experience, understanding and creative learning, which truly reflects this point.
2. Pay attention to students' emotions and attitudes, from creating teaching situations to stimulating students' interest, to guiding students to observe physical objects, encouraging students to adopt strategies of thinking, comparing, drawing and measuring, and let students participate in the whole learning process. Throughout the class, the students are playing middle school. Effective activities make every student move to study what this field is and use what they have learned to solve practical problems.