Thursday, December 14, 2023 I originally thought that after the epidemic, there would be no need for online teaching, but I didn't expect that because of the blizzard warning, the Education Commission asked students to study Xi online. As a teacher, I don't like online classes very much, on the one hand, I can't see the expressions and eyes of students when they listen to the class, and on the other hand, I don't have enough time to interact with students. The author's first year of work coincided with the epidemic, especially in the first half of 2020, when there were no classes in the first semester, and students listened directly to the live classes of the national education platform, and they did not have the opportunity to teach new classes. Looking back on the past three years of the epidemic, there are many classes that the author has not taught in person, which is very regrettable, and I hope that it can be accumulated little by little in the future. Yesterday, I switched to online classes again, although it will not last as long as the epidemic, but at present, new classes need to be opened according to the schedule, how to promote it so that students can also gain online classes?The author decided that it could only be explored in practice. First of all, before class, the author guides students to review the knowledge learned in the previous lesson "Area of Combined Figures", and then relate to the area of simple figures that we have learned before, so that we have mastered the calculation method of the area of simple figures and combined figures. Then show the scenario in the textbook, how to measure the size of a small footprintStudents who have had a pre-Xi can basically say how to use a number of squares and how to see an approximate figure, and then guide them to think about two questions: 1How to count squaresIf you use the method of counting squares, how do you count them?What is less than one grid?In this way, students are guided to find that when counting grids, count the whole grid first, if it is less than 1 grid and more than half a grid, it will be counted as one grid, and if it is less than half a grid, it can also be pieced together into 1 grid. 2.What kind of approximate figure do you see footprints as an approximate pattern?What do you think?In this process, the author guided the students to use the Tencent Meeting interactive annotation method to demonstrate their ideas, first of all, one student regarded the footprints as a triangle, and the specific graphics are as follows:
As you can see from the diagram, the triangle is much larger than the footprint, so how can we get the area as close to the true value of the footprint size as possible?Then the students used their brains to imagine different shapes (pictured): a quadrilateral (red), a trapezoidal (blue), and a rectangle (blue). Again, guide the students to observe: the same footprint, we can see different regular shapes, which one is best?Let students realize that although they can be seen as different figures, the essence is to approximate the irregular shapes to what kind of figures, so that the approximation of the area obtained is closest to the real value. 
Summary: Although this lesson is learning the area of irregular figures, the essence is to use old knowledge to solve new problems, different from the area of regular figures, when finding the area of irregular figures, it is through estimation or estimation to find an approximate value, in order to obtain the results as close as possible to the real value, it is necessary to think deeply about the method, the method of counting squares can be achieved by refining the size of the squares;The method of looking at it as an approximate figure can be regarded as an approximate polygon, and then calculated by dividing the polygon. In order to protect the health of students' eyesight, online classes are generally 25 minutes long, so the time for interaction will be relatively small, and there will be many students diving, but the author doesn't want to say anything, so while interacting with some students online, he also asked other students to interact and chat in the chat area, and the overall effect is not bad. In order to achieve classroom demonstration and pay attention to student feedback, the author will use two computers to log in, one for content ** and annotation, and the other to pay attention to student feedback and interaction, and the final effect is relatively satisfactory. 