In the teaching process, I explored the relationship between hand index and finger seam, demonstrated the relationship between the number of trees and the number of intervals with intuitive fingers, and created a problem situation to let students understand the application of intervals in life. In the part of breaking through the difficulties of this lesson, I use the courseware to demonstrate tree by tree, so that students can have a better solution to the complex problem of planting trees. "It's too much trouble to plant one tree at a time ..." Students came up with this idea and determined the "need for transformation". Then, the implementation strategy is generated and the feasibility of this method is verified. The students gave different answers to this example, leaving a blank here. Ask the students to explore the existence between the number of trees and the number of intervals by placing, counting and drawing learning tools: the number of trees = the number of intervals+1, and in turn verify which answer of the example is correct. In this process, students have completed the modeling of mathematical thoughts through constant observation, thinking and operation. But in the process of doing the problem, students still know but don't know why. "Why can't the problem of planting trees be taught repeatedly?" I made the following thoughts:

First of all, I only systematically explained the problem of planting trees in the Olympic math class. It doesn't appear in our math textbooks as a knowledge point, but only in the exercises, so we didn't spend time explaining it systematically in class.

Secondly, it is impossible to link the mathematical model in mind with the actual tree planting problem. Although I remember "five fingers are empty", it has nothing to do with practical problems such as installing street lamps, planting colorful flags and planting trees. They don't know what the distance between their fingers has to do with planting trees, installing lights and planting colorful flags.