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我听过许多以“对称”“轴对称图形”为内容的数学课,也看过不少同一内容的教学设计或教学实录,发现几乎都会犯概念不清楚、方法不科学之类的毛病,总的感觉是老师教得不清不楚,学生学得不明不白。下面先抄录几则教学片段,然后做一些评析。【教学实录1】出示蝴蝶、蜻蜓、树叶、热带鱼的图片。师:(学生动手探究后)你发现这些图形有什么共同特点?师:(师范对折)说得好!对折后,两边完全一样,一点不多,一点不少,我们就说这两边完全重合。师:(展示学生作品)同学们思考这些图形是对称的吗?为
I’ve heard many mathematical lessons that take “Symmetry ” “Axisymmetric Graphics ” as the content, and have seen quite a few teaching design or teaching records of the same content. I found that almost all of them make the concept unclear and the method unscientific The general feeling is that the teacher can not tell clearly unclear, students learn unclear. Let’s copy a few of the first tutorials and then make some comments. 【Teaching Record 1】 Presenting the pictures of butterflies, dragonflies, leaves and tropical fish. Teacher: (After the students explore) What are the common features found in these figures? Teacher: (Teacher’s Fold) Say it right! After the Fold, the two sides are exactly the same, a little more, a little more, and we say that the two sides completely coincide. Teacher: (Show student work) Students think these figures are symmetrical?