角的度量课件1.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,人教版新课标小学数学四年级上册,角的度量,角 的 度 量,边,边,顶点,角,角的度量,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,角的度量,量角器,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,外圈刻度,内圈刻度,刻度线,0,刻度线,0,刻度线,中心点,学习材料 一,1,、认识量角器各部分的名称,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,角的计量单位是“,度,”,用符号“,”,表示。把半圆分成,180,等份,每一份所对的角的大小是,1,度,记作,1,。,1,学习材料 二,2,、认识角的计量单位,10010,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,角的计量单位是“,度,”,用符号“,”,表示。把半圆分成,180,等份,每一份所对的角的大小是,1,度,记作,1,。,1,1,学习材料 二,2,、认识角的计量单位,1,3,、测量角的大小,1,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,（）,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,（）,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,（）,100,1010,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,130,50,量角器的,中心点,和角的,顶点,重合,。,量角器的,0,刻度线,和角的,一条边,重合,。,点,线,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,50,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,50,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,50,量角器的,中心点,和角的,顶点,重合,。,量角器的,0,刻度线,和角的,一条边,重合,。,看内圈或外圈读度数。,角的度量方法,：,1,、,我会量,。,1,1=（）,2,=（）,5,=,（）,3,=（）,2,3,4,125,45,30,30,5,4,=（）,90,角的大小与角的两边画出的,长短,没有,关系。,角的大小要看,两条边叉开的大小,，叉开得越大，角越大。,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,通过这节课的学习，你有什么收获？,用量角器量角时，你想提醒大家注意什么？,角的大小与角的两边画出的长短没有关系。,角的大小要看两条边叉开的大小，叉开得越大，角越大。,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,100,10,10,20,3040,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,1.,2.,5.,3.,4.,6.,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,仔细观察，量角器上有什么,?,外圈刻度,内圈刻度,刻度线,0,刻度线,0,刻度线,180,180,中心点,点,0,内,外,刻,2,、,我会读,。,6,0,1,3,0,75,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,仔细观察，量角器上有什么,?,外圈刻度,内圈刻度,刻度线,0,刻度线,0,刻度线,180,180,中心点,谢谢指导！,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,角的计量单位是“,度,”,用符号“,”,表示。把半圆分成,180,等份,每一份所对的角的大小是,1,度,记作,1,。,1,1,学习材料 二,2,、认识角的计量单位,顶点,角,100,10,10,20,30,40,50,60,70,80,90,80,70,60,50,40,30,20,180,180,110,120,130,140,150,160,170,170,160,150,140,130,120,110,100,量角器,角的度量,下面三个角中，哪个角最小？为什么？,量角的大小，要用量角器。,小多少呢,?,我画的角比你的小。,角 的 度 量,量角器的中心,量角器的,0,刻度线,量角器的内刻度,量角器的外刻度,量角器的,90,刻度线,180,180,180,180,180,180,180,180,180,180,仔细观察，量角器上有什么,?,角的计量单位是“,度,”,用符号“,”,表示。把半圆分成,180,等份,每一份所对的角的大小是,1,度,记作,1,。,1,用量角器量角的步骤,1,1,、把量角器放在角的上面；使量角器的中心和角的顶点重合；,2,、零度刻度线和角的一条边重合；,用量角器量角的步骤,1,1,、把量角器放在角的上面；使量角器的中心和角的顶点重合；,2,、零度刻度线和角的一条边重合；,3,、角的另一条边所对的量角器上的刻度，就是这个角的度数。,50,50,50,50,50,小组讨论,:,怎样测量下面两个角的度数,?,1,2,120,这是一个,6,0,的角？还是一个120,的角？,判断（请用手势“”或“”表示）。,这个角是,80,判断（请用手势“”或“”表示）。,这个角是,110,判断（请用手势“”或“”表示）。,这个角是,40,用量角器量下面的两组角，比较一下它们的,大小。,1,),30,),30,),60,90,130,角的大小与角的两边画出的长短没有关系。,角的大小要看两条边叉开的大小，叉开得越大,角越大。,你能发现什么,?,观察一下量角器，看看,30,45,60,90,120,有多大。,、,30,90,45,60,120,3.,先估计三角尺上各个角的度数，再量一量各是,多少度。,1.,下面的图形，哪些是直线,?,哪些是射线,?,哪些是,线段,?,(,1,),(,2,),(,3,),(,4,),(,5,),(,6,),(,7,),直线,线段,射线,射线,射线,直线,线段,2.,数一数，下图中各有几个角,?,3,个角,8,个角,3.,说出每个钟面上的时间，量出时针和分针所成的,角度。,60,90,120,150,4.,先估计，再量出图中各角的度数。,1=35,2=120,3=90,1,2,3,2.,量一量，下面的角各是多少度。,4,5,1,2,3,1=55,3=110,2=55,4=40,5=110,6.,用一副三角尺拼出下面度数的角。,75,105,120,135,150,180,8.*,数一数，下面的图形各有几个角,?,1,个角,3,个角,6,个角,你发现了什么规律,?,