【问题呈现】案例一:上课铃响之前,语文老师把班长叫到办公室,神秘地对他说:“老师有个天大的好消息要告诉同学们,你快回教室请大家坐好,等我来宣布!”班长回到教室一传达,教室里顿时像炸开了锅。学生纷纷猜测,有的说下午看电影,有的说明天春游,还有的说这一周没有家庭作业。 [Problem presentation] Case 1: Before the bell rang, the language teacher called the squad leader to the office and said mysteriously to him: “The teacher has a big good news to tell his classmates, Wait for me to announce! ”The monitor returns to the classroom as soon as the classroom suddenly exploded. Students have speculation, and some say afternoon watching movies, and some days of spring tour, others say there is no homework this week.