用計(jì)算器探索規(guī)律課件省公開課

MENTALHEALTHCOUNSELINGPPT3.6用計(jì)算器探索規(guī)律第三單元小數(shù)除法人教版小學(xué)數(shù)學(xué)五年級上冊第1頁游戲：猜數(shù)字從“1~9”這9個(gè)數(shù)字中選一個(gè)你最喜歡數(shù)想在心里，別說出來。如：我喜歡數(shù)字是“2”，就輸入9個(gè)“2”，然后把它除以“12345679”，除完以后你只要把結(jié)果告訴我，我很快就能知道你最喜歡數(shù)是幾。一、創(chuàng)境激疑第2頁4÷11＝__________

5÷11＝__________

用計(jì)算器計(jì)算下面各題。1÷11＝0.0909…2÷11＝0.1818…3÷11＝__________0.3636…

0.4545…

0.2727…你發(fā)覺了什么規(guī)律？循步驟它們商都是循環(huán)小數(shù)。二、互動解疑第3頁4÷11＝__________

5÷11＝__________

用計(jì)算器計(jì)算下面各題。1÷11＝0.0909…2÷11＝0.1818…3÷11＝__________0.3636…

0.4545…

0.2727…8÷11＝__________

9÷11＝__________

6÷11＝__________7÷11＝__________不計(jì)算，用發(fā)覺規(guī)律直接寫出下面幾題商。0.5454…

0.6363…

0.7272…

0.8181…123觀察發(fā)覺規(guī)律利用規(guī)律寫商用計(jì)算器計(jì)算三、啟思導(dǎo)疑第4頁3×0.73.3×6.7＝3.33×66.73.333×666.73.3333×6666.73.33333×66666.72.1＝＝＝＝22.11222.1112222.111122222.11111222222.111111＝3.333333×666666.72222222.1111111＝用計(jì)算器計(jì)算前四題，試著寫出后兩題積。[教材P35做一做]1234觀察發(fā)覺規(guī)律利用規(guī)律寫商用計(jì)算器計(jì)算依據(jù)規(guī)律寫算式四、實(shí)踐應(yīng)用第5頁1.用計(jì)算器計(jì)算前三題，找出規(guī)律，直接寫出后三題得數(shù)。1234.5679×9=____________________1234.5679×18=___________________1234.5679×27=___________________1234.5679×36=___________________1234.5679×45=___________________1234.5679×54=___________________11111.111122222.222233333.333344444.444455555.555566666.6666[教材P37練習(xí)八第12題]四、實(shí)踐應(yīng)用第6頁2.不計(jì)算，利用規(guī)律直接填出得數(shù)，再用計(jì)算器驗(yàn)算。6×0.7=4.26.6×6.7=44.226.66×66.7=_________6.666×666.7=__________444.2224444.2222[教材P37練習(xí)八第13題]下個(gè)算式是怎樣？結(jié)果是多少？＝6.6666×6666.744444.22222四、實(shí)踐應(yīng)用第7頁1÷7=2÷7=3÷7=4÷7=5÷7=6÷7=3.用計(jì)算器計(jì)算下面各題。0.142857142857···0.285714285714···0.428571428571···0.571428571428···0.714285714285···0.857142857142···不用計(jì)算,8÷7=__________________你發(fā)覺了什么？1.142857142857···四、實(shí)踐應(yīng)用第8頁五、總結(jié)評價(jià)第9頁4÷11＝__________

5÷11＝__________

1÷11＝0.0909…2÷11＝0.1818…3÷11＝__________0.3636…

0.4545…

0.2727…8÷11＝__________

9÷11＝__________

6÷11＝__________7÷11＝__________0.5454…

0.6363…

0.7272…

0.8181…123觀察發(fā)覺規(guī)律利用規(guī)律寫商用計(jì)算器計(jì)算4依據(jù)規(guī)律寫算式用計(jì)算器探索規(guī)律五、總結(jié)評價(jià)第10頁一、用計(jì)算器計(jì)算下面各題，說說發(fā)覺。1÷33=2÷33=3÷33=4÷33=5÷33=6÷33=7÷33=8÷33=9÷33=10÷33=0.0303···0.0606···0.0909···0.1212···0.1515···0.1818···0.2121···0.2424···0.2727···0.3030···六、鞏固練習(xí)第11頁二、不計(jì)算，利用規(guī)律直接寫出得數(shù)，再用計(jì)算器驗(yàn)算。1.4×6=243.4×6.6=22.443.34×66.6=222.4443.334×666.6=3.3334×6666.6=2.8.1÷9=0.988.2÷9=9.8888.3÷9=98.78888.4÷9=88888.5÷9=2222.444422222.44444987.69876.5六、鞏固練習(xí)第12頁三、找規(guī)律填一填。1.40102.5________________2.12