学生能够从现有材料中,经过动手,通过观察、分析、推理、归纳等思维过程,寻找出具有代表性的规律,归纳出普遍性的结论,是教师有效教学的重要体现.而形表结合是完成上述体现的有效途径.1、形表结合,有利于学生的观察.通过欣赏题目所给的图形,进行表格填空,不但能调动学生动手的主动性,而且能增加题目的直观性,有利于学生进行观察,学生处于有效的形表转换的思考状态. Students can find out the representative laws from the existing materials through hands-on thinking through observation, analysis, reasoning, induction and other generalized conclusions, which is an important manifestation of the effective teaching of teachers. Is to achieve an effective way to achieve the above .1, form combination, is conducive to student observation.Given the title given by the graphics, fill in the form, not only to mobilize the initiative of students, but also to increase the intuitiveness of the topic, there Which is conducive to students to observe, the students in a valid form conversion thinking.