二年级巧算速算教案_二年级巧算速算教案
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一。课题:
运算的速度来自运算技巧
二。教学要求:
熟练掌握凑十法:1+9=10,2+8=10,3+7=10,4+6=10,5+5=10
28+22=50,16+14=30,53+27=80,47+53=100,25+75=100 熟练掌握凑整法,为凑整可向其他数字借数,把其他数字拆开 三.教学过程
①引入方式 列举生活实例
②新概念如何讲
③例题
1.361-85-215
2.228-(128-66)
3.188-(128+45)
4.246-169+69 =361-(85+215)
=228-128+66
=188-128-45
=246-(169-69)=361-300
=100+66
=60-45
=246-100 =61
=166
=15
=146
5.96+(104-53)
6.837+(66-237)
7.273+297
8.497-298 =96+104-53
=837+66-237
=270+3+297
=497-300+2 =200-53
=837-237+66
=270+300
=197+2 =147
=666
=570
=199
一 基本题
1.29+54+71
2.99+15+85
3.76+24+38+62
4.97+23+77
5.1+3+5+7+9+11+13+15+17+19
6.1+3+11+17+49+99 7.13+14+15+16+17+55
8.2+3+15+36+27+85+64+88
9.5+6+7+8+9+10 10.2+13+25+44+18+37+56+75
11.31+32+33+34+35+36+37+38+39
12.23+54+17
13.35+19+31
14.24+45+55
15.52+36+48
16.15+21+85+19 17.20+68+32+80
18.72+84+28+16
19.469+58+31
20.41+42+43+44+45
21.2+4+6+8+9+5+7+1+3
22.53+54+47+46
23.28+59+13+72+41
24.44+55+66+56+45+34
25.81+23+35+48+77+52+19+65
二典型题
1.96+16
2.77+12-27
3.54-35+46
4.85+19
5.83+99
6.27+75
7.53+35-33+65
8.54-40+36-32+38-24 9.10-20+30-40+50-60+70-80+90
10.20-19+18-17+16-15+14-13+12-11
11.56+36-40-30-46+68
12.36-35+34-33+32-31
13.(22+24+26+28+30)-(21+23+25+27+29)14.11-12+13-14+15-16+17-18+19-20+21
15.(2+4+6+8+……+30)-(1+3+5+……+29)
16.(2+4+6+……+100)-(1+3+5+……+99)
17.37+95 18.48+84
19.66-21+34
20.59+48-29
21.167+35-67
22.89+29+19
23.67+97+6
24.15+25-35+45-55+65-75+85
25.97+57+47+9
26.478-128+122-72
27.1870-280-520
28.464-545+99+345
29.537-(543-163)-57
30.4995-(995-480)
31.4250-296+96
32.947+(572-447)-372
33.7443+2485+245+567
34.437-(37-25)
35.63+54+128+37-28
36.2000-253-1347+1596
37.666+(268-166)
38。321-243+143
39.3675-(12+14+16+18+20)
40.8376+1548+62-3248
41.526+112+88-56-44-26
42.437-33-34-43-237
43.499-(173+27+99)
44.923-(423-188)
45.298+68
46.(287+503-113)-(303-213)
47.572-395
48.1006-398
49.9+99+999
50.2691+842+309
51.397+47
52.836-596
53.446-99-9
54.236+164+68
55.458-99
56.6471-2471-3250
57.3007+498-2998
58.1541-499
59.2745-396
60.1534+498
61。958-596
62.328-199
63.780+370-580-170
64.380-(250+450)
65.998+199+97+6
66.9999+999+99+9+4
67.3996-1998+2994
68.109+98+497+1696
69.858-597
70.写出9+9+9+9+9+5的三种简便方法