練習(xí)十二,復(fù)習(xí)舊知,課堂小結(jié),課后作業(yè),小數(shù)的初步認(rèn)識(shí),鞏固練習(xí),7,復(fù)習(xí)舊知,列豎式計(jì)算。,1.80.2 0.40.9 50.3,1.8, 0.2,1,0,2,2,0.4, 0.9,1,3,1,1.3,5, 0.3,3,5,5.3,先把小數(shù)點(diǎn)對(duì)齊，也就是相同數(shù)位對(duì)齊，再按照整數(shù)加法法則計(jì)算，得數(shù)的小數(shù)點(diǎn)要和加數(shù)的小數(shù)點(diǎn)對(duì)齊。,先把小數(shù)點(diǎn)對(duì)齊，也就是相同數(shù)位對(duì)齊，再按照整數(shù)減法法則計(jì)算，得數(shù)的小數(shù)點(diǎn)要和減數(shù)的小數(shù)點(diǎn)對(duì)齊。,列豎式計(jì)算。,0.90.1 2.40.6 50.6,0.9, 0.1,8,0,0.8,2.4, 0.6,.,8,1,1.8,5, 0.6,4,4,4.4,.,先提出問(wèn)題再解答。,天安門城樓高34.7米,人民英雄紀(jì)念碑高37.9米,人民英雄紀(jì)念碑比天安門城樓高多少米？,人民英雄紀(jì)念碑比天安門城樓高多少米？,37.934.7,37.9, 34.7,.,2,3,3.2（米）,答：人民英雄紀(jì)念碑比天安門城樓高3.2米。,鞏固練習(xí),填空。,1.一支鉛筆0.2元，一支圓珠筆1.5元。一支鉛筆和一支圓珠筆一共（ ）元。 2.小明的身高是1.4米，小明比小華高0.2米，小華的身高是（ ）米。 3.被減數(shù)是12.1，減數(shù)是8.3，差是（ ）,0.21.51.7,1.7,1.40.21.2,1.2,12.18.33.8,3.8,列豎式計(jì)算。,3.73.4 10.40.9 56.3,3.7, 3.4,1,1,7,7.1,10.4, 0.9,1,3,11,11.3,5, 6.3,3,11,11.3,列豎式計(jì)算。,4.80.5 8.41.7 62.6,4.8, 0.5,3,4,4.3,8.4, 1.7,.,7,6,6.7,6, 2.6,4,3,3.4,.,先計(jì)算，再進(jìn)行比較。,4.30 4.3,6.23.2 8.9,0.60.7 1.4,1.10.3 0.7,91.3 8.7,3.72.1 2,4.3,一支鉛筆0.8元，一支鋼筆比它貴8.6元，小明拿10元錢買一支鋼筆和一支中性筆，錢夠嗎？,先求出一支鋼筆的價(jià)錢，再求一共多少錢？,8.60.8,9.4（元）,答：買一支鋼筆和一支中性筆，錢不夠。,0.89.4,10.2（元）,10.210,所以不夠,一個(gè)大桶里有10.8千克水，倒入小桶里2.2千克水后，大桶和小桶里的水一樣重，小桶里原有水多少千克？,先求大桶倒出2.2千克后重多少？,10.82.2,8.6（千克）,答：小桶里原有水6.4千克。,8.62.2,6.4（千克）,8.6千克為小桶被倒入2.2千克后的重量。,課堂小結(jié),小數(shù)的加法法則,先把小數(shù)點(diǎn)對(duì)齊，也就是相同數(shù)位對(duì)齊，再按照整數(shù)加法法則計(jì)算，得數(shù)的小數(shù)點(diǎn)要和加數(shù)的小數(shù)點(diǎn)對(duì)齊。,課堂小結(jié),小數(shù)的減法法則,先把小數(shù)點(diǎn)對(duì)齊，也就是相同數(shù)位對(duì)齊，再按照整數(shù)減法法則計(jì)算，得數(shù)的小數(shù)點(diǎn)要和加數(shù)的小數(shù)點(diǎn)對(duì)齊。,課后作業(yè),1.從教材課后習(xí)題中選??； 2.從課時(shí)練中選取