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现象一:在一节“轴对称图形”课上,当学生通过“折纸—剪纸—观察”等一系列活动,发现轴对称图形的特征后,教师让学生从学具袋中取出事先准备好的三角形、长方形、圆等8个已学过的平面图形,要求学生折一折,看能发现什么。学生通过独立操作和小组交流后,一致认为:长方形、正方形、圆、等腰三角形、等腰梯形是轴对称图形;一般三角形、一般梯形、平行四边形不是轴对称图形。从表面上看,教学效果不错,但我们总觉得少了点什么,这节课学生收获了什么?难道仅仅是判断某一图形是不是轴对称图形吗?
Phenomenon One: After a series of activities such as “origami - paper cutting - observation ” and the like were found in a section of Axisymmetric Graphics, the teacher removed the student from the sachet Prepared triangles, rectangles, circles, etc. have been learned eight planar graphics, students are asked to fold, see what can be found. Students through independent operation and group exchange, agreed that: rectangular, square, circle, isosceles triangle, isosceles trapezoid axisymmetric graphics; general triangle, generally trapezoidal, parallelogram is not axisymmetric graphics. On the surface, the teaching works well, but we always feel less at what, what is harvested in this lesson? Is it just a matter of judging whether a shape is an axisymmetric shape?