[教学片断]一排学生手举自转旋翼站在高约1米的主席台上。“预备———放!”随着一声令下,只见一排自转旋翼从相同的高度纷纷落下,犹如天女散花,异彩纷呈,同学们高兴地看着比赛。这是豫版《科学》三年级上册《自转旋翼》一课的教学情境之一。三次比赛之后,我问道:“谁的自转旋 [Piece of Teaching] A row of students hold their own rotating rotor standing about 1 meter high on the podium. “Prepare --- put!” With the order, I saw a row of autorotate rotor from the same height have fallen, like a lotus flower scattered, colorful, students are happy to watch the game. This is the Yu version of “Science” third grade on the “Rotor” a teaching situation. After three matches, I asked: "Whirlwind rotation