Interpretation and analysis: arrange ten triangles in two rows, so that they differ by four, that is, seven in a row and three in a row. There are ten triangles here, which we can combine into any shape. As long as we put two squares with a difference of four, then we take out seven squares and put them in a row, and multiply them by three squares, so that ten triangles are put in two rows with a difference of four.

Related knowledge points: move more and make up less

1. Organizing thematic classroom activities in application problem teaching is beneficial to improve the efficiency of application problem teaching; It is helpful for students to look at things around them from a mathematical perspective, find mathematical problems and gain a lot of direct experience, so as to actively construct knowledge, form mathematical models and gain strong emotional experience. It is also beneficial for teachers to make good use of teaching materials and improve their ability to implement new courses.

2. In order to highlight the principle of "let students understand' shift 1 difference 2'"; Understanding the key point of mastering the quantitative relationship of the application problem of "move more and make up less", students began to imagine different methods of arranging eight bookshelves in two rows, which not only penetrated the limit idea, but also solved the problem. Then through hands-on operation, we finally explore different ways to solve the problem.

Then, on the basis of understanding and mastering the problem-solving methods, let students answer independently and encourage different thinking methods. Through variant exercises, it can be tested whether students really master the quantitative relationship of application problems with more actions and less supplements, and test their learning and flexible application ability.