whiteboard with grid.There are still many such examples. For example, when introducing the reference object in "Mechanical Movement", the teacher first introduces an example: a building with a height of 291.6 meters being built on a square site , a colorful cloud drifting quickly When the building was over, suddenly someone exclaimed that ??the building was going to fall down??, which caused thousands of people to panic and rush, and then the building did not show signs of collapse, and then asked the students: Why do everyone agree that the building wants Collapsed? Then naturally over-learning to the reference. Another example is: For example, before learning "atmospheric pressure", the teacher holds a large test tube filled with water, and then puts a small test tube in a large test tube filled with water, asking the students: When I put each other in the sleeve The two tubes are turned upside down with their nozzles facing down and the small tubes falling from the large tubes. The students answered in unison: "It will definitely fall." So after the teacher turned the two tubes back, the small test tube not only fell from the big test tube, but rose along the wall of the large test tube, even vertically. Jitter, the small test tube still does not fall out of the large test tube. Strong contradictions and conflicts have ignited the students?? pursuit of the bottom line. What the hell is going on? Everyone learns the "atmospheric pressure" and will understand.