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《直线和射线》是人教版课标实验教材《数学》四年级上册的教学内容。案例一、认识直线、射线1,依托“有限”认识“无限线”师(拿出可以射出红色光束的教学演示用笔,先打开开关,在墙上投射出一个细小的红点,再用一只手将光线挡住):如果是在漆黑的夜晚,大家能在我的两只手之间看到什么?生1:一条红色光线。生2:一条直直的、细细的线。(教师请一名学生在黑板上画一条直直的线)师:大家继续想象,这条光线从“激光笔”发射出来,能向后退吗?遇
“Line and ray” is the PEP teaching material “Mathematics” fourth grade on the teaching content. Case 1, to know the line, ray 1, relying on “limited ” understanding “Infinity Line ” division (out of the teaching demonstration pen can emit a red beam, first open the switch, cast a small red dot on the wall , Then use one hand to block the light): If it is dark night, what can we see between my two hands? Health 1: a red light. Health 2: A straight, thin line. (Teacher asked a student to draw a straight line on the blackboard) Teacher: We continue to imagine that this light is emitted from the “laser pointer”, can it be retreated?