Introduction/Posing Problem 
The teacher asks which is faster Shinya or Toru, Toru or Shigeki. He confirms that we can compare the speeds when one pair of the numbers is the same. He asks who is faster, Shinya or Shigeki. (5:41) 

Solving Problem 
Students work independently on the problem that the teacher posed. While each student works on the problem, the teacher observes how each student is solving the problem, considering in what sequence the various solution strategies may be shared and discussed. (0:34) 

Sharing/Make Distance LCM 
One student makes the distance 200m. Another student observes that 200 is LCM of 40 and 50. (4:39) 

Sharing/Make Time LCM 
One Student makes the times equal. She makes the time 72 seconds, the LCM of 8 and 9, then multiples it by the distance. She concludes that the one who runs 400m is faster than the one who runs 360m because he runs for the same time. (4:09) 

Sharing/Make Distance 40m 
One student finds seconds per 1m of Shigeki by using a double number line diagram. Then he multiplies it by 40 to get the time for 40m. (2:51) 

Sharing/Make Distance 1m 
One Student asks whether it is necessary to compute the time for 40m against "Make Distance 40m" method. Then another student suggests that getting the time for 1m is enough. (3:24) 

Sharing/Make Time 1s 
One student expresses the idea of making seconds equal to 1 using a double number line. Then the teacher shares with the students that the longer distance means faster when the time is matched. (3:17) 

Summary 
The teacher reviews the lesson. He concludes that we define "distance per second" by how far someone can run in a second. (2:03) 
