.door whiteboard.Diverse and richly-characterized illustrations are an important part of the textbook. In the teaching, the use of electronic whiteboards creates a dynamic situation, and the activity process is fully displayed with vivid colors and active images, so that the key points can be highlighted and the difficulties can be overcome. The abstraction is concrete, and it can promote the thinking orientation from fuzzy to clear. Make primary school students understand the concepts and operations in mathematics through an intuitive image. In the teaching of "column calculation of two digits by one digit multiplication", the explanation of the reason is quite troublesome, and the abstract and boring explanation is also easy for the students to hear. If you use animation, it is much better. For example: 48??2, put 8 bundles on the left side with 10 sticks (10 bundles each), and put 16 on the right side. Use animation to display 10 bundles from the 16 on the right. The bundle is placed on the left side, so there are 9 bundles in the whole bundle, and 6 bundles remain on the right side, so 48??2=96 (root). In this way, the principle of the carry is visualized in front of the students.