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小學(xué)數(shù)學(xué)五年級(jí)上冊(cè),折紙,制作：嚴(yán)坑小學(xué)龍丹紅,折紙,（分?jǐn)?shù)加減法（一））,教學(xué)目標(biāo),教學(xué)重、難點(diǎn),學(xué)具準(zhǔn)備,教學(xué)過(guò)程,教學(xué)目標(biāo),1、理解分?jǐn)?shù)加減混合運(yùn)算的順序。,2、能正確計(jì)算分?jǐn)?shù)加減混合運(yùn)算。,返回,教學(xué)重、難點(diǎn),理解異分母分?jǐn)?shù)加減法的算理；能正確計(jì)算異分母分?jǐn)?shù)的加減法。,返回,學(xué)具準(zhǔn)備,紙片,彩色筆,尺子,返回,請(qǐng)同學(xué)們把下面各組分?jǐn)?shù)通分：,1,,3,和,5,,9,1,,5,和,2,,7,5,,6,和,3,,4,復(fù)習(xí),,,,,9,和,5,,9,35,,7,和,35,,10,12,,10,和,12,,9,3,返回,,同學(xué)們?cè)谑止ふn上折紙。小紅用了一張紙的折一只小船，小明用同一張紙的折一只小鳥(niǎo)。,1,,2,1,,4,(1)他倆一共用了這張紙的幾分之幾？,,,,,,,,,+,﹦,1,,2,1,,4,3,,4,,,,1,2,,1,,4,3,,4,+,﹦,返回,,,,,,,,+,﹦,,,1,2,,3,,4,,,,,,,,,,,,,,,+,﹦,2,,4,1,,4,3,,4,哈哈!變成同分母的分?jǐn)?shù)就可以加法計(jì)算了!,1,,4,1,,2,1,,4,+,﹦,12,,22,+,1,,4,﹦,3,,4,返回,,,同學(xué)們?cè)谑止ふn上折紙。小紅用了一張紙的折一只小船，小明用同一張紙的折一只小鳥(niǎo)。,1,,2,1,,4,(2)小紅比小明多用了這張紙的幾分之幾?,,,,,,,,,,,—,﹦,1,,2,1,,4,1,,4,,,,1,2,,1,,4,返回,,,1,,4,–,＝,,,,—,﹦,,,1,2,,,,,,,,,,,,,,,—,﹦,2,,4,1,,4,1,,4,哈哈!變成同分母的分?jǐn)?shù)就可以減法計(jì)算了!,,,,,1,,4,1,,4,1,,2,1,4,,－,＝,12,,22,－,1,4,,＝,1,4,,返回,,,試一試,3,,4,5,8,＋,,9,10,1,6,－,,,＝,＝,42,32,8,5,＋,,,＝,6,8,5,8,,＋,,＝,11,8,1,8,3,,＝,,93,103,15,65,,,－,＝,27,30,5,30,22,30,11,15,,,,,－,＝,＝,返回,,,更多資源,初二語(yǔ)文初二英語(yǔ)初二數(shù)學(xué)初二物理初二政治初二歷史初二地理初二生物,?,?,?,怎樣計(jì)算分母不同的分?jǐn)?shù)加減法呢?,分母不同的分?jǐn)?shù)相加減，要先通分，化成相同的分母，再加減。,計(jì)算結(jié)果能約分的，要約成最簡(jiǎn)分?jǐn)?shù)。如果是假分?jǐn)?shù)的要化成帶分?jǐn)?shù)或整數(shù)。,小結(jié),返回,,,練一練,2,3,1,4,＋,＝,8,12,3,12,11,12,＋,＝,,,,,,1,－,2,5,5,5,2,5,3,5,＝,＝,,,,,＝,－,返回,,更多資源,