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[教学前思]“角的度量”是北师大版小学数学四年级上册一节操作技能课。此前,学生已学会运用直尺测量长度的方法,然而,量角器的结构与直尺大相径庭:量角器呈半圆形,标有内外两圈刻度,有两个“0”起点。能否跳出测量长度的思维定势探究出度量角的方法?这是对学生已有认知的挑战,于是,让学生熟知度量角的工具——量角器的构造和测量原理应是本课的教学重点。在日常教学中,对于操作技能课教学往往是先由
[Thinking before teaching] “angle measurement ” is a version of the operation of the Northwest Normal University grade four grade book. Previously, students had learned to use rulers to measure length. However, the structure of the protractor was quite different from that of a ruler: the protractor was semicircular with two inner and outer ring marks and two “0” start points. Is it possible to jump out of the measurement length of the mind set to explore the method of measuring the angle? This is a cognitive challenge to the students, so let students familiar with the measurement angle tool - protractor construction and measurement principle should be the teaching of this lesson Focus. In everyday teaching, teaching of operating skills is often the first lesson