一、教学内容与教材分析《连续退位减》是第四册数学第七单元“万以内的加法和减法(二)”中第二节“笔算减法”中的教学内容 ,分3课时学完 ,这节课是第一课时的新授课 ,教学P99的例5、例6 ,完成“做一做”的两道题和练习二十六的1-3题。此前 ,学生已学习了“不连续退位的减法” First, the teaching content and textbook analysis “continuous abatement by subtraction” is the fourth volume of mathematics seventh unit “within thousands of addition and subtraction (two)” in Section II “pen calculation subtraction” in the teaching content, finished in 3 hours, This lesson is a new lecture in the first class, teaching P99 cases 5, 6, to complete the “do one” two questions and exercises twenty-six 1-3 questions. Previously, students had studied “subtraction of discontinuity abortions”