小学三年级上册数学秒的认识PPT课件(已修整).ppt
,12,1,2,3,4,5,6,7,8,9,10,11, , , , , .,12,12,5,60,12,1,2,3,4,5,6,7,8,9,10,11, , , ,12,1,2,3,4,5,6,7,8,9,10,11, , 1 ,12,1,2,3,4,5,6,7,8,9,10,11, 1 1 .,12,1,2,3,4,5,6,7,8,9,10,11, 500 ., 1 105 ,1 2700 ., 7900 ., 1 ., 3 ., .,1,12,1,2,3,4,5,6,7,8,9,10,11, 5 5 ,12,1,2,3,4,5,6,7,8,9,10,11, 1 ( ) ( ) .,5,5, : 12 3 ., 12 6 ,15,30,12,1,2,3,4,5,6,7,8,9,10,11,秒针共走过6大格,也就是30小格。是30秒。, : 10 .,: 10 ,10,12,1,2,3,4,5,6,7,8,9,10,11, ., .,1=60,1. 3 6 ,2. 10 ( ) 15 .3. ( ) 8 10 .,1. 8 9 .( ),5. . ( ),4. . ( ),3. 8 9 5 .( ),2. 8 9 .( ), ., ., ( ) 7 15( ) 20( ) 30 ( ). 2 ( ) 7( ) 10( ) 20 ( ) 1 ( ) . 10 10 14 .,1号:我跑了11秒,2号:我跑了9秒,3号:我跑了10秒,50米比赛中,跑得最快的是( )号,2,小小裁判员,1- 11,2- 9,3- 10,50 ( )- .,2, :, 47 , 47 , :, :, 47 ,:, 40 1 , !, 6 1 , ,