(一)性别决定 1.导入新课教师在黑板上写出“人体的发育是从卵细胞开始的”,让学生判断这句话是否正确。如果不正确,指出错误所在。实践证明,一般学生都能够把错的地方找出来,但也有少部分学生模糊不清。然后,让学生打开课本(甲种本)第60页倒数第7行,念“人体的发育是从受精卵这一个细胞开始的。” (A) of the sex decision 1. Import a new lesson Teachers write on the blackboard “human development begins from the egg cells,” so that students can judge whether this sentence is correct. If not correct, indicate the error. Practice has proved that most students are able to find the wrong place, but there are a small number of students blurred. Then ask the students to open the seventh line from the bottom of page 60 of the textbook, “The development of the human body starts with a cell of the fertilized egg.”