中小学课件 课题《口算乘法》例1.pptxVIP

人教版三年级下册课题《口算乘法》例1授课教师：单 位：快速说出下面算式的结果。6个26×3＝1215186×2＝3×5＝ 20个23020×2＝4010×5＝5010×340＝15＋50＝18＋30＝16×3＝48( )×( )＝65( )×2＝5226135你有什么发现吗？每筐装15盒草莓，买了3筐，一共买了多少盒草莓？15×3＝你会列式吗？你会口算吗？想一想：怎么算？写出你的口算过程。00:0002:0002:0001:5901:5801:5701:5601:5501:5401:5301:5201:5101:5001:4901:4801:4701:4601:4501:4401:4301:4201:4101:4001:3901:3801:3701:3601:3501:3401:3301:3201:3101:3001:2901:2801:2701:2601:2501:2401:2301:2201:2101:2001:1901:1801:1701:1601:1501:1401:1301:1201:1101:1001:0901:0801:0701:0601:0501:0401:0301:0201:0101:0000:5900:5800:5700:5600:5500:5400:5300:5200:5100:5000:4900:4800:4700:4600:4500:4400:4300:4200:4100:4000:3900:3800:3700:3600:3500:3400:3300:3200:3100:3000:2900:2800:2700:2600:2500:2400:2300:2200:2100:2000:1900:1800:1700:1600:1500:1400:1300:1200:1100:1000:0900:0800:0700:0600:0500:0400:0300:0200:01每筐装15盒草莓，买了3筐，一共买了多少盒草莓？45(盒) 15×3＝拆分10×3＝30仔细回想15×3的口算过程。15你能读懂他的想法吗？5×3＝1510530＋15＝45用学过的方法口算下列算式。 11×5＝5655 14×4＝15×6＝90 23×4＝92请选择其中一个算式，说一说你是怎样算的。00:0000:2000:2000:1900:1800:1700:1600:1500:1400:1300:1200:1100:1000:0900:0800:0700:0600:0500:0400:0300:0200:01写出你的口算过程。450 150×3＝100×3＝30050×3＝150300＋150＝45015×3＝45，150×3＝450。45个十15个十 × 3 =把其中一个乘数拆分，再分别与一位数相乘，最后把两次乘得的积相加。填一填。（数学书P43第1题）27×3180×537×801005 ×5×20×36040050021＋＋90081想一想，它们相同的地方是什么？00:0000:2000:2000:1900:1800:1700:1600:1500:1400:1300:1200:1100:1000:0900:0800:0700:0600:0500:0400:0300:0200:01仔细观察，你又发现了什么？1、口算下面的题目。（数学书P41做一做）11×5＝5655 14×4＝110×5＝ 560 550 140×4＝15×6＝90 23×4＝92150×6＝ 900 230×4＝ 920 先不看零，口算出结果后再在结果后面添上零。口算几百几十乘一位数时，2、解决问题。（数学书P43第3题）（1）3辆车最多可坐多少人？21×3＝63（人）（2）80人乘坐这4辆车，能坐下吗？答：3辆车最多可坐63人。01:0000:0001:0000:5900:5800:5700:5600:5500:5400:5300:5200:5100:5000:4900:4800:4700:4600:4500:4400:4300:4200:4100:4000:3900:3800:3700:3600:3500:3400:3300:3200:3100:3000:2900:2800:2700:2600:2500:2400:2300:2200:2100:2000:1900:1800:1700:1600:1500:1400:1300:1200:1100:1000:0900:0800:0700:0600:0500:0400:0300:0200:012、解决问题。（数学书P43第3题）（2）80人乘坐这4辆车，能坐下吗？80÷4＝21×4＝20（人）84（人）21人＞20人84人＞80人答：80人乘坐这4辆车， 能坐下。答：80人乘