【2020新】北師大版四年級數(shù)學(xué)下冊《15街心廣場》課件

1、 街心廣場 （建議一課時(shí)完成）第三單元 小數(shù)乘法 四年級下冊 課后作業(yè)探索新知積的小數(shù)位數(shù)與乘數(shù)的小數(shù)位數(shù)的關(guān)系1課堂探究點(diǎn)2課時(shí)流程課堂小結(jié)當(dāng)堂檢測北師大版四年級數(shù)學(xué)下冊20米30米北師大版四年級數(shù)學(xué)下冊探究點(diǎn) 積的小數(shù)位數(shù)與乘數(shù)的小數(shù)位數(shù)的關(guān)系先說一說街心廣場上的數(shù)學(xué)信息，再算一算，填一填。街心廣場花壇地磚面積/平方米北師大版四年級數(shù)學(xué)下冊淘氣在計(jì)算地磚的面積時(shí)遇到了困難，你能幫幫他嗎？0.30.2 （ ）0.3米3分米0.2米2分米326（平方分米）6平方分米0.06（平方米）6（平方米）0.3米0.2米321米1米0.01平方米6個(gè)0.01是0.06平方米。0.06

2、平方米北師大版四年級數(shù)學(xué)下冊結(jié)合上面的計(jì)算過程，想一想乘數(shù)和積之間有什么關(guān)系。30 206003 2 6北師大版四年級數(shù)學(xué)下冊積的小數(shù)位數(shù)與乘數(shù)的小數(shù)位數(shù)有什么關(guān)系？算一算，想一想。0.10.30.1320.130.2第一個(gè)乘數(shù)的小數(shù)位數(shù)第二個(gè)乘數(shù)的小數(shù)位數(shù)積的小數(shù)位數(shù)0.260.026011112202213北師大版四年級數(shù)學(xué)下冊小試牛刀（源于典中點(diǎn)）1算一算。(1)10101000. 1 8北師大版四年級數(shù)學(xué)下冊(2)北師大版四年級數(shù)學(xué)下冊2填一填。(1)一個(gè)乘數(shù)擴(kuò)大到原來的10倍，另一個(gè)乘數(shù)擴(kuò)大到原來的100倍，積就擴(kuò)大到原來的( )倍。(2)一

3、個(gè)乘數(shù)縮小到原來的 ，另一個(gè)乘數(shù)也縮小到原來的 ，積就縮小到原來的()。1000北師大版四年級數(shù)學(xué)下冊3把表格補(bǔ)充完整，你發(fā)現(xiàn)了什么？我發(fā)現(xiàn)：_。算式第一個(gè)乘數(shù)的小數(shù)位數(shù)第二個(gè)乘數(shù)的小數(shù)位數(shù)積的小數(shù)位數(shù)0.0330.090.20.28202001112兩個(gè)乘數(shù)一共有幾位小數(shù)，積就有幾位小數(shù)(答案不唯一)北師大版四年級數(shù)學(xué)下冊4根據(jù)第一欄的積快速寫出后面每欄的積。乘數(shù)12121.21.2121201.2乘數(shù)1515050.15積1801800181.818180.18北師大版四年級數(shù)學(xué)下冊歸納總結(jié)：（講解源于典中點(diǎn)）兩個(gè)數(shù)相乘，每一個(gè)乘數(shù)都乘(或除以)一

4、個(gè)不為0的數(shù)，它們的積就乘(或除以)這兩個(gè)不為0的數(shù)的乘積。北師大版四年級數(shù)學(xué)下冊小試牛刀（教材P39練一練）你會計(jì)算這塊拼圖的面積嗎？想一想，算一算。 （1）與同伴交流你的想法。 （2）結(jié)合計(jì)算過程說一說，積的 小數(shù)位數(shù)與乘數(shù)的小數(shù)位數(shù) 有什么關(guān)系？略。9(平方米)積的小數(shù)位數(shù)是乘數(shù)的小數(shù)位數(shù)之和。北師大版四年級數(shù)學(xué)下冊根據(jù)第一欄的積很快寫出后面每欄的積。乘數(shù)363.6363.60.36乘數(shù)242.42.4242.4積8648.6486.486.40.864北師大版四年級數(shù)學(xué)下冊淘氣的計(jì)算器上的小數(shù)點(diǎn)無法顯示了，你能幫他得到正確答案嗎？北師大版四年級數(shù)學(xué)下冊明明每天上學(xué)和放

5、學(xué)都要乘坐一次公交車，每乘一次公交車花0.2元。明明的公交卡里還剩3元，夠他一周5天上學(xué)和放學(xué)用嗎？0.220.4（元）0.452（元）夠他一周5天上學(xué)和放學(xué)用。根據(jù)1312156，在 里填上適當(dāng)?shù)臄?shù)。13 1.2 1.3 1.21.312 13 2 1.31200.13 1.2 130 1.2點(diǎn)撥：答案不唯一。易錯(cuò)辨析5判斷。(對的畫“”，錯(cuò)的畫“”)(1)2.45的積的小數(shù)位數(shù)有0位。()(2)0.1258的積有三位小數(shù)。()辨析：兩個(gè)乘數(shù)一個(gè)共有幾位小數(shù)，積就有幾位小數(shù)。版權(quán)申明本文部分內(nèi)容，包括文字、圖片、以及設(shè)計(jì)等在網(wǎng)上搜集整理.版權(quán)為個(gè)人所有This artic

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21、all not misinterpret or modify the original intention of the content of this article, and shall bear legal liability such as copyright.版權(quán)申明本文部分內(nèi)容，包括文字、圖片、以及設(shè)計(jì)等在網(wǎng)上搜集整理.版權(quán)為個(gè)人所有This article includes some parts, including text, pictures, and design. Copyright is personal ownership.用戶可將本文地內(nèi)容或服務(wù)用于個(gè)人學(xué)習(xí)、研究或

22、欣賞，以及其他非商業(yè)性或非盈利性用途，但同時(shí)應(yīng)遵守著作權(quán)法及其他相關(guān)法律地規(guī)定，不得侵犯本網(wǎng)站及相關(guān)權(quán)利人地合法權(quán)利.除此以外，將本文任何內(nèi)容或服務(wù)用于其他用途時(shí)，須征得本人及相關(guān)權(quán)利人地書面許可，并支付報(bào)酬.Users may use the contents or services of this article for personal study, research or appreciation, and other non-commercial or non-profit purposes, but at the same time, they shall abide by the

23、 provisions of copyright law and other relevant laws, and shall not infringe upon the legitimate rights of this website and its relevant obligees. In addition, when any content or service of this article is used for other purposes, written permission and remuneration shall be obtained from the perso

24、n concerned and the relevant obligee. 轉(zhuǎn)載或引用本文內(nèi)容必須是以新聞性或資料性公共免費(fèi)信息為使用目地地合理、善意引用，不得對本文內(nèi)容原意進(jìn)行曲解、修改，并自負(fù)版權(quán)等法律責(zé)任.Reproduction or quotation of the content of this article must be reasonable and good-faith citation for the use of news or informative public free information. It shall not misinterpret or modif

25、y the original intention of the content of this article, and shall bear legal liability such as copyright.版權(quán)申明本文部分內(nèi)容，包括文字、圖片、以及設(shè)計(jì)等在網(wǎng)上搜集整理.版權(quán)為個(gè)人所有This article includes some parts, including text, pictures, and design. Copyright is personal ownership.用戶可將本文地內(nèi)容或服務(wù)用于個(gè)人學(xué)習(xí)、研究或欣賞，以及其他非商業(yè)性或非盈利性用途，但同時(shí)應(yīng)遵守著作權(quán)法

26、及其他相關(guān)法律地規(guī)定，不得侵犯本網(wǎng)站及相關(guān)權(quán)利人地合法權(quán)利.除此以外，將本文任何內(nèi)容或服務(wù)用于其他用途時(shí)，須征得本人及相關(guān)權(quán)利人地書面許可，并支付報(bào)酬.Users may use the contents or services of this article for personal study, research or appreciation, and other non-commercial or non-profit purposes, but at the same time, they shall abide by the provisions of copyright law

27、and other relevant laws, and shall not infringe upon the legitimate rights of this website and its relevant obligees. In addition, when any content or service of this article is used for other purposes, written permission and remuneration shall be obtained from the person concerned and the relevant

28、obligee. 轉(zhuǎn)載或引用本文內(nèi)容必須是以新聞性或資料性公共免費(fèi)信息為使用目地地合理、善意引用，不得對本文內(nèi)容原意進(jìn)行曲解、修改，并自負(fù)版權(quán)等法律責(zé)任.Reproduction or quotation of the content of this article must be reasonable and good-faith citation for the use of news or informative public free information. It shall not misinterpret or modify the original intention of the content of this article, and shall bear legal liability such as copyright.版權(quán)申明本文部分內(nèi)容，包括文字、圖片、以及設(shè)計(jì)等在網(wǎng)上搜集整理.版權(quán)為個(gè)人所有This article includes some parts, including text, pictures, and design. Copyright is personal ownership.用戶可將本文地內(nèi)容或服務(wù)用于個(gè)人學(xué)習(xí)、研究或欣賞，以及其他非商業(yè)性或非盈利性用途，但同時(shí)應(yīng)遵守著作權(quán)法及其他相關(guān)法律地規(guī)定，不得侵