smartboard troubleshooting.According to different teaching contents , we can also use the way of games to arouse students' desire to learn. Such as the introduction of "Density" teaching. Set up a series of guessing games , show two cups of liquid , a glass of water , a cup of alcohol to identify which cup is water and which cup is alcohol. Show two pieces of metal , one piece of copper , one piece of iron , to identify which piece is copper and which piece is iron. We have concluded that substances can be identified using the properties of substances such as color and odor. Then design a small game : two pieces of the same size of copper and iron pieces in the white paper , let the students identify, then some students said that the weight is the copper block, the secret is the case, the teacher proposed this comparison Is the light and heavy method to identify the substance really reliable? Design a small game again, let the students identify the copper and iron pieces that are different in shape, volume, weight and weight in the white paper. It is thus introduced that the size of the mass should be compared under the same volume conditions , and the concept of density is further introduced.