“常见的数量关系”是苏教版《义务教育教科书·数学》四年级下册第三单元“三位数乘两位数”中的一项内容。“总价、单价和数量”“路程、时间和速度”是学生在小学阶段认识的两个重要的数量关系,也是基本的数学模型。面对新增教学内容,如何把握总价、单价和数量以及路程、时间和速度的教学价值?如何帮助学生理解单价、速度的概念及其单位所表示的含义?如何促进学生建构“总价、单价和数 ”Common quantitative relationship “ is the Sujiao version of ”compulsory education textbook mathematics“ fourth grader third unit ”three digits by two digits “ in a content. ”Total Price, Unit Price and Quantity “ Distance, Time, and Speed ​​ ”are two important quantitative relationships that students recognize in elementary school and are also basic mathematical models. How to grasp the teaching value of total price, unit price, quantity, distance, time and speed? How to help students to understand the concept of unit price and speed and the meaning of their unit? How to promote the construction of students , Unit price and number