,第4课时 认识0,新课导入,随堂演练,第,4,课时简单的计算,(,一,),（一）我会填。,3元6角=(36 )角,75角=(7 )元(5 )角,100分=(10 )角,8角+6角=(14 )角=(1 )元(4 )角,3元2角-2元=(1 )元(2 )角,3元4角+5角=(3 )元(9 )角,4元7角-6角=(4 )元(1 )角,（二）我会选(将准确答案的序号填在括号里 )。,1.1元2角+2元3角=()角。,303540,2.一袋面包3元,一包饼干4元,买这两样东西至少要带()钱。,7元10元1元,3.买一双袜子7元钱,小丽付了一张10元钱,应找回()。,17元3角3元,（三）我会比(在里填上”或=”)。,（四）我会判。,他们都买了一本故事书(6元8角 ),谁的钱付対了,就在谁旁边的()里画”。,（五）我会解答。,4,元,5,角,8,角,3,.,至少要花多少钱,才能买到两样东西,?,3,元,7,角,同学们，你们要相信梦想是价值的源泉，相信成功的信念比成功本身更重要，相信人生有挫折没有失败，相信生命的质量来自决不妥协的信念，考试加油,!,奥利给,结束语,20,以内的退位减法,整理和复习,17,6,1,3,7,14,8,1,5,3,11,9,16,6,计算接力赛,2,11,6,12,6,10,17,6,11,1,3,7,6,1,4,8,6,1,5,3,12,1,1,9,2,16,6,10,计算接力赛,退位,不退位,20,以内的退位减法,十几,减,9,十几减,8,、,7,、,6,十几减,5,、,4,、,3,、,2,回顾梳理本单元内容,计算,解决问题,晶晶,整理复习,沟通联系,合作要求:,2人为一组,先说一说晶晶是怎样整理的,再把余下的算式填出来,然后用你喜欢的方式快速算出每道算式的结果,写在算式的后面,最后看看算式的排列有什么规律。,观察退位减法表,12,9,3,14,9,5,16,9,7,15,9,6,17,9,8,18,9,9,13,9,4,11,9,2,12,8,4,12,75,12,66,12,57,12,48,12,39,13,8,5,13,76,13,67,13,58,13,49,14,8,6,14,77,14,68,14,59,15,87,15,78,15,69,16,88,16,79,17,89,1183,1165,1174,1156,1147,1138,1129,12,9,3,14,9,5,16,9,7,15,9,6,17,9,8,18,9,9,12,8,4,12,75,12,66,12,57,12,48,12,39,13,8,5,13,76,13,67,13,58,13,49,14,8,6,14,77,14,68,14,59,15,87,15,78,15,69,16,88,16,79,17,89,13,9,4,11,9,2,1183,1165,1174,1156,1147,1138,1129,11,11,11,11,11,11,11,11,1,1,1,1,1,1,1,1,1,1,1,1,1,1,观察退位减法表:横看,计算第一行算式,你能发现什么？,2,3,4,5,6,7,8,9,被减数不变,减数越小,差越大。,3,4,5,6,7,8,9,被减数不变,减数越小,差越大。,12,9,3,14,9,5,16,9,7,15,9,6,17,9,8,18,9,9,13,9,4,11,9,2,12,8,4,12,75,12,66,12,57,12,48,12,39,13,8,5,13,76,13,67,13,58,13,49,14,8,6,14,77,14,68,14,59,15,87,15,78,15,69,16,88,16,79,17,89,1183,1165,1174,1156,1147,1138,1129,12,8,4,12,75,12,66,12,57,12,48,12,39,13,8,5,13,76,13,67,13,58,13,49,14,8,6,14,77,14,68,14,59,15,87,15,78,15,69,16,88,16,79,17,89,1183,1165,1174,1156,1147,1138,1129,1,1,1,1,1,1,1,1,1,1,1,1,1,1,观察退位减法表:竖看,计算第一列算式,你能发现什么？,竖着看,你发现了什么？,2,3,4,5,6,7,8,9,减数不变,被减数越大,差也越大。,4,5,6,7,8,9,减数不变,被减数越大,差也越大。,观察退位减法表,12,9,3,14,9,5,16,9,7,15,9,6,17,9,8,18,9,9,13,9,4,11,9,2,12,8,4,12,75,12,66,12,57,12,48,12,39,13,8,5,13,76,13,67,13,58,13,49,14,8,6,14,77,14,68,14,59,15,87,15,78,15,69,16,88,16,79,17,89,1183,1165,1174,1156,1147,1138,1129,减数和被减数同时增大1,差不变。,同学们,你们能把差是 6 的算式一组一组地说出来吗？,11-5=6,12-6=6,13-7=6,14-8=6,15-9=6,10-4=6,9-3=6,8-2=6,7-1=6,让我来考考你吧。,解决问题,1293朵,12,9,小林比小丽少得了几朵？,小丽和小林的红花相差几朵？,口答:小丽比小林多得了3朵。,第一关:夺红旗,3,6,6,6,5,5,5,5,12-3=9,第二关:摘苹果,13-8=5,第二关:摘苹果,13-6=7,第二关:摘苹果,11-8=3,第二关:摘苹果,15-7=8,第二关:摘苹果,15-8=,5,10-,2,3,准确做法:,第三关:下面计算有错误吗？,15-8=,5,10-,2,14-5=,4,10-,5,9,14-5=11,7,14,8 6,只,第四关:生活中的数学,第五关:在 里该填什么数？,9-4=11-,14-5=2+,5,6,9,7,课堂检测,