In the first lecture, I directly import a paragraph of text, so that students can estimate the total number of words after listening. Half of the students took out their fingers and pointed to the display screen, counting while ignoring the teacher's request to "estimate".

In the second lecture, I tried to make students realize that estimation is essential in some cases, that is, the necessity and advantages of experiencing estimation. I redesigned the lead and used a photo of people watching the performance, which made it difficult and unnecessary for them to count the exact number of people. At this time, the requirement of estimation arises. Then, let them estimate at will, and the results are quite different. Here's another hint: there are about 200 people in a red box. According to this standard, students can estimate more reasonably.

Due to the change of this link, in the next link, when the number of words is estimated, almost no one will use the number method again.

From this, I also realized that the highest realm of teaching is teaching without trace.