根据提供的信息和语言素材设计教学方案，用英文作答。
设计任务：请阅读下面学生信息和语言素材，设计20分钟的英语读写教学方案。
该方案没有固定格式，但须包含下列要点：
teaching objectives
teaching contents
key and difficult points
major steps and time allocation
activities and justifications
教学时间：20分钟
学生概况：某城镇普通中学初中三年级(九年级)学生，班级人数40人，多数学生已经达到
《义务教育英语课程标准(2011年版)》三级水平。学生课堂参与积极性一般。
语言素材：
Who invented tea?
Did you know that tea, the most popular drink in the world (after water), was invented by accident? Although tea wasn′t brought to the western world until 1610, this beverage was discovered over three thousand years before that. According to an ancient Chinese legend, the emperor Shen Nong discovered tea when he was boiling drinking water over an open fire. Someleaves from a nearby bush fell into the water and remained there for some time. The emperor noticed that the leaves in the water produced a pleasant smell. Later he decided to taste the hot mixture. It was quite delicious. And in this way, one of the world′s favorite drinks was invented.