物理变化和化学变化的本质是看是否产生了新的物质。要区分纸撕碎和纸燃烧两种变化各属于哪一类变化,就要看在变化过程中是否产生了新的物质。对于学生来说,就是要找到更多的证据来证明在变化的过程中产生了新的物质。而学生寻找的过程就是以学生为主体的过程,是培养学生科学素养的过程,是学生成长的过程。 The essence of physical and chemical changes is to see if new substances have been created. To distinguish between paper shredding and paper burning two kinds of changes belong to what kind of change depends on whether there is a new material in the process of change. For students, it is to find more evidence to prove that in the process of change has created a new material. The process of student seeking is student-centered process, which is the process of training students 'scientific accomplishments and the process of students' growth.