Unit 5 Why do you do that

教学目标

教学目标与要求
　　通过本单元教学，使学生学会使用表示目的用语，并运用到日常交际。复习一般现在时，一般过去时和含有情态动词的被动语态的用法。使学生学会写种植西红柿的过程。

教学的重点和难点
Words and expressions
burn, free, operate, obey, punish, so that, in order to, make sure, stop. . . (from) doing
Daily expressions
　　1）I’ll keep the box in the shade so that the sun doesn’t bum the little plants．
　　2）I’ll water them to stop the soil getting too dry．
Grammar
　　1.Ways of expressing purposes
　　2.Revision of the Passive Voice