四年級下冊圖形的旋轉(zhuǎn).ppt

課件PPT,1.2旋轉(zhuǎn),第1單元平移、旋轉(zhuǎn)、軸對稱,課件PPT,1、進(jìn)一步認(rèn)識圖形的旋轉(zhuǎn)，認(rèn)識按順時(shí)針或逆時(shí)針方向旋轉(zhuǎn)90的含義。2、能在方格紙上把簡單圖形旋轉(zhuǎn)90，畫出旋轉(zhuǎn)后的圖形。3、掌握旋轉(zhuǎn)的三要素。,學(xué)習(xí)目標(biāo),課件PPT,從這幅圖中你看到了哪些運(yùn)動(dòng)？,探究新知,大家認(rèn)真自學(xué)書上第3頁的例2，并思考下面的問題（5分鐘）導(dǎo)學(xué)問題：1、圖中的轉(zhuǎn)桿打開和關(guān)閉分別是怎樣運(yùn)動(dòng)的？有什么相同點(diǎn)和不同點(diǎn)？2、轉(zhuǎn)桿的打開和關(guān)閉，分別繞哪個(gè)點(diǎn)按什么方向旋轉(zhuǎn)的?旋轉(zhuǎn)了多少度？3、你能完整地描述轉(zhuǎn)桿打開和關(guān)閉的過程嗎？,轉(zhuǎn)桿打開和關(guān)閉，它們的運(yùn)動(dòng)有什么相同點(diǎn)和不同點(diǎn)？,相同點(diǎn)：轉(zhuǎn)桿打開和關(guān)閉都是繞著一個(gè)點(diǎn)旋轉(zhuǎn)。,不同點(diǎn)：轉(zhuǎn)桿打開和關(guān)閉旋轉(zhuǎn)的方向正好相反。,與時(shí)針旋轉(zhuǎn)方向相同的是順時(shí)針，與時(shí)針旋轉(zhuǎn)方向相反的是逆時(shí)針。,順時(shí)針方向,逆時(shí)針方向,從6：00到9：00，時(shí)針旋轉(zhuǎn)了（）。,90,A,你會(huì)把右邊的三角板繞A點(diǎn)旋轉(zhuǎn)90。嗎？,A,把三角板繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,把三角板繞A點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,旋轉(zhuǎn)有哪三要素？1、旋轉(zhuǎn)中心。（繞某點(diǎn)）2、旋轉(zhuǎn)方向。（順時(shí)針或逆時(shí)針）3、旋轉(zhuǎn)角度。（旋轉(zhuǎn)90度或其他角度）完整描述旋轉(zhuǎn)：某圖形繞某點(diǎn)順時(shí)針（或逆時(shí)針）旋轉(zhuǎn)多少度。如：三角形繞點(diǎn)A逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,A,B,把長方形繞A點(diǎn)順時(shí)針旋轉(zhuǎn)90。,把小旗圖繞B點(diǎn)逆時(shí)針旋轉(zhuǎn)90。,課件PPT,指針按順時(shí)針方向旋轉(zhuǎn)90。，從A旋轉(zhuǎn)（）；,指針按逆時(shí)針方向旋轉(zhuǎn)90。，從B旋轉(zhuǎn)（）。,B,A,錯(cuò)誤解答,課件PPT,錯(cuò)解分析：,與時(shí)針旋轉(zhuǎn)方向相同的是順時(shí)針方向，與時(shí)針旋轉(zhuǎn)方向相反的是逆時(shí)針方向。,指針按順時(shí)針方向旋轉(zhuǎn)90。，從A旋轉(zhuǎn)（）；,指針按逆時(shí)針方向旋轉(zhuǎn)90。，從B旋轉(zhuǎn)（）。,D,C,正確解答,課件PPT,你見過生活中的哪些旋轉(zhuǎn)現(xiàn)象？你能說出來嗎？,課件PPT,旋轉(zhuǎn)有哪三要素？1、旋轉(zhuǎn)中