Stimulate students' interest in learning mathematics, cultivate students' interest in thinking. Interest is the motive force of students' active learning, especially for the primary school students, interest plays a very important role in their learning process, to stimulate students' interest in learning mathematics is the first problem that teachers should solve. Situation teaching is an effective way to arouse students' interest in learning. For example, teachers can set such questions when teaching unit price calculation. Ōbana goes to the store to buy erasers, pencils and schoolbags, can you do the math for her? Ask groups of students to investigate the price of pencils, erasers, and schoolbags before class. ASK students to answer this question based on their own research, and the unit price question will be raised. The teacher creates the situation which is equal to the student's thinking level properly, it is bound to raise the student's interest in study, and also promote the development of the student's thinking level to a certain extent.