Unit 3 Lets go to the Underwater World.Instructional DesignTeaching objectives: language function:The Imperative sentence to express their wishes.Language Structure: Lets go to the Underwater World. Term: master vocabulary: library, world understanding of vocabulary: a public holiday, Underwater World, restaurant, hospital, science story, idea, picnic Syntax: from Lets. Constitute the imperative sentence.Period 1Teaching aims:1. can understand, will say the new word