Teachers are the organizers, guides and collaborators of students' mathematical activities; According to the specific situation of students, the teaching materials are reprocessed and the teaching process is creatively designed; It is necessary to correctly understand the individual differences of students, teach students in accordance with their aptitude, and let each student develop on the original basis; Let students have a successful experience and establish self-confidence in learning mathematics well.
(1) Let students learn mathematics in vivid and concrete situations.
In this period of teaching, teachers should make full use of students' life experience and design vivid, interesting and intuitive mathematics teaching activities, such as telling stories, playing games, intuitive demonstrations and simulated performances, so as to stimulate students' interest in learning and let students understand and know mathematics knowledge in vivid and concrete situations. For example, teachers can instruct students to play the following games.
Example 1 Two students play a guessing game in pairs.
A: I thought of a two-digit number. Can you guess what it is?
B: Is this number greater than 50?
A: That's right.
B: Is it less than 70?
A: That's right.
B: Is it greater than 60?
A: No.
B: Is it greater than 56?
……
Teachers can use the above games to guide students to engage in interesting mathematical activities, so that students can learn an effective problem-solving strategy while experiencing the size of numbers, which contains the simple idea of gradually approaching with "interval sets".
(2) Guide students to think independently and cooperate and communicate.
Hands-on practice, independent exploration and cooperative communication are important ways for students to learn mathematics. In this period of teaching, teachers should let students think independently in specific operational activities, encourage students to express their opinions and communicate with their peers. Teachers should provide appropriate help and guidance, be good at choosing valuable questions or opinions among students, and guide students to discuss in order to find the answers to questions.
Example 2 When rotating the turntable (see the right), is it more likely that the pointer will fall in the shadow area or the white area?
In teaching, the teacher can first group the students, let each student guess in advance which area the pointer will stop, and then start to turn the turntable. In the process of personally rotating the turntable, students realize that it is uncertain whether the pointer falls in the shadow area or the white area before the turntable stops. After many rotations, students gradually realize that the number of times the pointer falls in the shadow area is different from that in the white area, and the number of times the pointer stops in the white area is more than that in the shadow area, that is, the possibility of the pointer falling in the white area is greater than that of the pointer. On the basis of students' hands-on operation, teachers can guide students to discuss and exchange their feelings.
In the teaching of "Space and Graphics", teachers should design colorful activities, so that students can further understand their own space and know some common geometric bodies and plane graphics through observation, measurement, folding and discussion. For example, in the teaching of identifying cuboids, cubes, cylinders and spheres, teachers should select materials from objects familiar to students (such as basketball, table tennis, beverage bottles, kaleidoscopes, chalk boxes, toothpaste boxes, globes, etc.). ), and encourage students to observe, touch and classify, thus forming an intuitive feeling of related geometry. For another example, the following activities can be designed in teaching: let four students sit in four directions and observe the same object (such as kettle, teacup, etc.). ), draw what they see first, then organize students to communicate and guess who drew a picture and where he sat. Through observation, comparison and imagination, students realize that what they see in different directions is different, and gradually develop the concept of space.
(3) Strengthen estimation and encourage diversification of algorithms.
Estimation is widely used in daily life. In this stage of teaching, teachers should seize the opportunity to cultivate students' estimation consciousness and preliminary estimation skills.
Example 3 Xiaoming earned 243 yuan from raising chickens and 479 yuan from raising pigs. What is the estimated income of these two items?
Different students may have different estimation strategies. Some students think that "200 plus 400 equals 600, 43 plus 79 is greater than 100, so their sum is a little more than 700"; Some students' estimation methods may be: "243 is less than 250 and 479 is less than 500, so their sum is less than 750;" Some students may say that "this number is more than 200+400 and less than 300+500", which is correct. Teachers should organize students to exchange estimation methods, compare estimation results, and gradually cultivate students' estimation consciousness and strategies.
Because students' life background and thinking angle are different, the methods used are inevitably diverse. Teachers should respect students' ideas, encourage students to think independently and advocate diversification of calculation methods. For example, students can use various methods to calculate the problem of 34+27, and the methods listed below should be encouraged.
( 1)
(2) 34+27
=34+20+7
=54+7
=6 1
(3) 30+20=50 (4)34+27
4+7= 1 1 =34+6+2 1
50+ 1 1=6 1 =40+2 1
34+27=6 1 =6 1
Teachers should not be eager to evaluate various algorithms, but should guide students to choose their own methods by comparing the characteristics of various algorithms. For another example, when solving the problem that "at the parent-teacher conference, each bench can hold up to 5 people, and 33 parents need to prepare at least several benches", students' thinking methods may be diverse. Some students use learning tools, sticks represent benches, and disks represent parents. It is concluded in the operation that at least 7 benches should be prepared. Some students judged that at least 7 benches should be prepared by calculating 33÷5. Some students use multiplication, 5× 7 = 35, 35 > 33, 5× 6 = 3030 < 33, so at least 7 benches should be prepared. Teachers should encourage these methods, provide opportunities for students to communicate, and let students constantly improve their methods in mutual communication. This can not only help teachers understand the learning characteristics of different students, but also help to promote the development of students' personality. At the same time, teachers should always ask students to think about such questions: What do you think? What did you do just now? What if? What's the matter? Which method do you think is better? ..... so as to guide students to think and exchange solutions to problems.