Introduction/Posing Problem 
The teacher places a table that shows a first grade student runs 40m in 8 seconds and sixth grade student runs 100m in 16 seconds on the blackboard. At first, the teacher asks the students which one is faster. Students determine sixth grade student is faster. After that, the teacher poses following problem.
"We want to make this two students finish at the same time. The distance is 120m, and they start at the same time. How many meters ahead should the first grade student start?" (6:31)


Solving Problem/List answers 
After the teacher poses the problem, he has students work independently for 9 minutes. After the individual work, he asks students for their answers. The teacher lists these answers on the blackboard. (4:26)


Sharing/Find Time and Speed 
The teacher asks the student who gave 24m as an answer how to solve the problem. The student explains that she found the time that that a sixth grade student would need 96/5 sec to run 120 m, and also the speed of the first grade student. Then she calculated the speed of the first grader. Then she calculated the distance the first grader would run in 96/5 sec and subtracted that from 120m. (5:23)


Sharing/Reverse Arrow 
The teacher asks if they want to add anything. One student says she drew her arrow for the 1st grader going backwards from the end. (2:26)


Sharing/Proportional Relationships 
One student explains that she found the answer by using a proportional
distance and time for both the 1st and 6th graders. (6:10)


Sharing/Expand Distance 
The student says his idea was based on lengthening the distance of the 6th grade student. (2:28)


Discussion/Is This Way Correct? 
The teacher and the students discuss if the approach of lengthening the 6th grader's distance would work.. (4:05)


Sharing/Calculate Time 
The teacher asks the students if they could verify whether the lengthening method would work or not. One student explains that he calculated the time of the 1st grader for 120m and of the 6th grader for 150m, and found they're same. (1:44)


Sharing/Speed Difference 
One student expresses his idea of finding the speed difference between the 6th and 1st graders, then multiply it by seconds to find the difference in the distances. (5:34)

