一、联系旧知识,导入新课指定学生说出百以内数的减法法则,教师板书:计算100以内数的减法,相同数位对齐。从个位减起,个位不够减,从十位退一,个位加10再减。〔百以内数的减法法则,是计算万以内数的减法的基础,通过学习让学生抓住了新知识的支撑点,为知识迁移作好准备。〕 First, contact the old knowledge, import the new class Specify the number of students to subtract the law within a hundred, the teacher's letter: subtract the number of less than 100, the same digit alignment. Subsequent from the individual bit, a bit less than minus, from the ten back to a place plus 10 minus. [The subtraction rule of one hundred in number is the basis for calculating the subtraction of ten thousands. By learning, students are allowed to seize the support of new knowledge and prepare for the transfer of knowledge. ]