Because this is the first time for students to contact the word "perimeter", only through observation, operation and personal experience can students understand the meaning of perimeter in specific situations. In class, first of all, I create a vivid and interesting situation, presenting a story of an ant climbing the edge of a leaf, stimulating students' interest in learning, and letting students initially perceive the words "week" and "perimeter"; Then let the students draw their favorite leaves and the graphics on the exercises in the textbook with colored pens to further intuitively perceive the perimeter, so that the students can draw that the perimeter of the graphics is the length of a week; Then ask the students to find examples around them to tell what its circumference is, and touch its circumference with their hands to expand their perceptual knowledge of the circumference and understand its significance initially. Finally, let the students measure and calculate, and let them use the knowledge of perimeter to calculate the perimeter of regular graphics and the extension of knowledge.
Although this course attaches importance to the process of knowledge formation and acquisition, and provides students with a lot of practical activities to strengthen their feelings and experiences of mathematical knowledge, there are still some problems.
First of all, I think there is a design that digs too deeply into the content of the textbook. I designed six figures to let students judge which figures have perimeters and which figures have no perimeters. Why? After the students answered, I came to the conclusion that only closed figures have perimeters, and the two are not closed figures. The purpose is to make students feel that the edge of the figure is closed, so that they know that when referring to the circumference of the surface of an object, they must point completely and not break it. In fact, in the following link, students are required to point to the perimeter, which implies that students can experience this characteristic of perimeter. So there is no need to emphasize the end-to-end connection of the sideline, and the effect is not very good.
Secondly, the details need to be refined. For example, in the "try it" session, when students measure the perimeter of leaves by themselves, I found that students' choice of measurement methods is very random, and the whole measurement process takes a lot of time. I think it is because of the lack of guidance for students to choose methods before measurement. If you add "How are you going to measure it?" Before measurement. The discussion of the problem may avoid the above problems. Some students said that after winding the leaves with a rope, straighten the rope and measure it with a ruler to know what the perimeter of the leaves is. At this time, I didn't seize the opportunity to infiltrate students with the mathematical idea of "turning curves into straight lines" For another example, when calculating the perimeter of figures in actual operation, I showed the fourth question in the textbook Thinking and Doing, in which the first figure is an isosceles triangle, the second is an equilateral triangle, and the third is a parallelogram. Among them, it embodies a transition from general to special. Many students choose to use simple multiplication to calculate, but I didn't seize the opportunity to make them understand the intention of the text. If students can talk about why multiplication can be used according to the actual situation of graphics, I believe students will have a deeper understanding of the text.
In addition, there is a lack of teaching evaluation. When students can't make timely and accurate evaluation after answering, or when students have different opinions, they can't seize the opportunity to guide students and make evaluation in time, which is where we should pay attention and work hard in the future.
I was deeply moved by this lecture. I think a good class is full of energy, and this energy comes from students' feelings and experiences about events or facts, from students' sensitivity and curiosity about problems, from rich and active guesses and assumptions, from the collision, debate, enlightenment and recognition of different viewpoints. And this is what my class lacks. Through this lecture combined with the study of the annual meeting, I really understand that an effective math problem, a valuable math problem, is actually the collision of students' thinking, the sublimation of ideas and the infiltration of mathematical methods. So I think in my future teaching, I will try my best to provide students with space for thinking, communication, practice and inquiry, and guide students to experience and understand the formation process of knowledge. Let students feel and experience the colorful world around them, discover and enhance the beauty of mathematics, let students get nourishment from classroom learning in many ways, and let the classroom become the home for students' spiritual enjoyment.
Therefore, I think the most soul thing that teachers use to shape a good class is to be able to shuttle freely between texts, dig out the mysteries contained in them and present what they have learned to students in simple terms.