Unit 3 What were you doing when the UFO arrived ?Teaching goals:1. Words : barber shop , well , bathroom , accident , earth , silence , playground , around , strange , kitchen , modern , follow , shirt .2. when , while 引导的时间状语从句。3. 学习过去进行时态。4. 利用知识谈论过去发生的事情。5. 复习过去式，学会讲故事。6. 了解一些自然科学知识和社会科学知识。Important and difficult points:1. when, while 引导的时间状语从句。2. 学习过去进行时态。Teaching aids: a tape-recorder, cards. Period 1Teaching procedures:Step 1 Leading in 1. Greetings a
