小数的意义 (2).ppt
西师版四年级(下),小 数 的 意 义,0.46,0.239,文龙小学 周熠,姚明身高 2.26米,我的50米赛跑成绩是7.98秒。,“中国飞人”刘翔在2004年雅典奥运会110米栏的决赛中以12.91秒的成绩获得冠军。,0 1 2 3 4,1米,振 兴 中 华 努 力 学 习,看一看:我们教室里的黑板有多长?它是整米数吗?,例:1角=( )元=( 0.1)元 5角=( )元=( )元 例:1分米=( )米=( )米 3分米=( )米=( )米,0.5,0.1,0.3,热身准备,照例子,填一填。,分数:( ),小数:( ),0.1,0.7,有7个0.1,1,根据每个图中的涂色部分写数。,分数:( ),小数:( ),分数:,分数:,小数:,小数:,( ),( ),( ),( ),0.01,0.45,有45个0.01,填一填:1mm = ( ) m = ( )m 146 mm =( )m = ( )m,把1m平均分成1000份,其中1份是 1 mm。,1000,1,0.146,146,1000,0.001,2,填一填,说一说。,0.001,0.025,0.107,(有25个0.001),(有107个0.001),把1个正方体平均分成1000份:,说一说:三位小数表示( )分之几,千分之几用( )位小数表示。,千,三,你认为什么样的数叫小数?,像0.7,0.45,0.025,0.107这样,用来表示十分之几、百分之几、千分之几的数,叫做小数。,小数的计数单位有0.1,0.01, 0.001 ,小数中,每相邻两个计数单位之间的进率是( ),0.1,0.01,10,里面有10个,数位顺序表,一(个),十分位,百分位,千分位,万分位,0.1,0.01,0.001,0.0001,分数:_,小数:_,分数:_,小数:_,分数:_,小数:_,看图填数。,练习1,0.2,0.23,0.203,在图中,分别用阴影表示下面各小数。,0.6,0.08,0.42,练习2,0.6 =,( ),6,0.87 =,( ),87,0.025 =,( ),25,在( )里填上合适的数。,练习3,10,100,1000,0.81,0.048,0.15,填一填,1、0.8的计数单位是( ),有( )个这样的计数单位。,2、0.06的计数单位是( ),有( )个这样的计数单位。,3、0.134的计数单位是( ) ,有( )个这样的计数单位。,0.1,8,0.01,6,134,0.001,练习4,谢 谢,