资源描述
20以内的进位加法、 退位减法整理和复习,整理数学算式,6+9,5+9,4+9,3+9,2+9,9+4,8+5,7+7,6+6,3+8,9+5,8+3,7+4,按什么规律整理呢?,6+9,5+9,4+9,3+9,2+9,9+4,8+5,7+7,6+6,3+8,9+5,8+3,7+4,你,说,我,说,6+5,6+6,6+7,6+8,6+9,5+6,5+7,5+8,5+9,4+7,4+8,4+9,3+8,3+9,2+9,9+2,9+3,9+4,9+5,9+6,9+7,9+8,9+9,8+3,8+4,8+5,8+6,8+7,8+8,8+9,7+4,7+5,7+7,7+8,7+9,7+6,你,说,我,说,6+5,6+6,6+7,6+8,6+9,5+6,5+7,5+8,5+9,4+7,4+8,4+9,3+8,3+9,2+9,9+2,9+3,9+4,9+5,9+6,9+7,9+8,9+9,8+3,8+4,8+5,8+6,8+7,8+8,8+9,7+4,7+5,7+7,7+8,7+9,7+6,9,+,?,你,说,我,说,6+5,6+6,6+7,6+8,6+9,5+6,5+7,5+8,5+9,4+7,4+8,4+9,3+8,3+9,2+9,9+2,9+3,9+4,9+5,9+6,9+7,9+8,9+9,8+3,8+4,8+5,8+6,8+7,8+8,8+9,7+4,7+5,7+7,7+8,7+9,7+6,你,说,我,说,6+5,6+6,6+7,6+8,6+9,5+6,5+7,5+8,5+9,4+7,4+8,4+9,3+8,3+9,2+9,9+2,9+3,9+4,9+5,9+6,9+7,9+8,9+9,8+3,8+4,8+5,8+6,8+7,8+8,8+9,7+4,7+5,7+7,7+8,7+9,7+6,11,12,13,14,15,16,17,18,你,说,我,说,6+5,6+6,6+7,6+8,6+9,5+6,5+7,5+8,5+9,4+7,4+8,4+9,3+8,3+9,2+9,9+2,9+3,9+4,9+5,9+6,9+7,9+8,9+9,8+3,8+4,8+5,8+6,8+7,8+8,8+9,7+4,7+5,7+7,7+8,7+9,7+6,8 + 3 = 3 +,2 + 9 = 9 +,5 + 6 = 6 +,7 + 5 = 5 +,8 + 3 = 3 +,8,方法一,11,8 + 3 = 3 +,8,方法二,8 + 3 = 3 +,2 + 9 = 9 +,5 + 6 = 6 +,7 + 5 = 5 +,8,5,2,7,闯关大本营,3 + 9 =,4 + 7 =,8 + 6 =,5 + 7 =,9 + 6 =,3 + 8 =,4 + 6 =,8 + 5 =,9 + 9 =,20 以内退位减法表,横着看,第一行 都是 11 减几。,11减几,12减几,13减几,14减几,15减几,16减几,17减几,18减几,2,3,4,5,6,7,8,9,被减数不变,减数变小,差变大,横着看,第一行的得数有什么规律?,20 以内退位减法表,竖着看,第一列 都是减 9 的。,十几减9,十几减8,十几减7,十几减6,十几减5,十几减4,十几减3,十几减2,2,3,4,5,6,7,8,9,被减数变大,减数不变,差变大,那竖着看你又发现了什么?,. 你还能发现什么有规律的排列?,算一算,你会有更多的发现。,你还可以怎样看?,3,4,5,6,7,8,9,4,5,5,6,6,6,7,7,7,7,8,8,8,8,8,9,9,9,9,9,9,斜着看,被减数变大,减数也随之变大,差不变。,2,3,5,8,4,6,7,9,小朋友们,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。,儿歌,退位减,我会算 十几减9,是几加1, 十几减8,是几加2, 十几减7,是几加3, 十几减6,是几加4, 十几减5,是几加5。,智勇大冲关,第一关:看图列算式,7,5,12,5,7,12,12,7,5,12,5,7,8,7,15,7,8,15,15,8,7,15,7,8,第二关:想加算减,3 + 8 = 11 - 3 = 11 - 8 =,4 + 9 = 13 - 4 = 13 - 9 =,5 + 7 = 12 - 5 = 12 - 7 =,11,8,3,13,9,4,12,7,5,11 - 8,12 - 6,13 - 7,14 - 9,15 - 9,12 - 7,13 - 8,11 - 6,第三关:争小红旗,第四关:争当神算手,9 + 8 = 11 - 6 = 16 - 9 = 15 - 7 = 3 + 8 = 12 - 5 =,12 - 6 = 8 + 7 = 15 - 6 = 14 - 5 = 7 + 7 = 14 - 6 =,14 - 8 = 13 - 6 = 7 + 9 = 6 + 6 = 13 - 7 = 12 - 9 =,17,6,6,5,15,7,7,9,16,8,9,12,11,14,6,7,8,3,头好晕啊!我投降了,17 - 8 - 3 = 11 - 6 + 7 = 5 + 4 + 6 =,9 + 4 - 6 = 5 + 9 - 8 = 8 + 7 - 9 =,6 12 15,7 6 6,第五关:看谁最棒,谢谢!,
展开阅读全文