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在《圆柱的认识》教学中,我通过三次对“旋转”的观察与想象,帮助学生认识圆柱。第一次“旋转”教师出示一个长方形木框,指出:这是一个长方形框,如果以长边所在直线为轴进行旋转,想象一下,会转成一个什么图形?学生想象、交流。第二次“旋转”屏幕出示一个圆柱体。教师提问:现在我们再来猜想一下,屏幕上的这个圆柱,是由怎样的一个长方形旋转而成的呢?
In “Knowledge of Cylinder” teaching, I help students to know the cylinder by observing and imagining “Rotation” three times. For the first time, the teacher of “Rotation” presents a rectangular wooden frame, pointing out: This is a rectangular box. Imagine what it will turn into if it is rotated with the straight line on the long side. Students imagine and communicate. The second “Rotation ” screen shows a cylinder. Teacher Question: Now let’s guess what kind of a rectangle this column on the screen is made of.