Algebraic Expressions Lesson 4 Episode 1 (Teachers)

Making Sense

No captions toggle left Captions
Stop the video above first if it is playing.

Download Math TaskLink to Geogebra applet Link to on-line calculator

ET and Haleemah make sense of the scooter applet and create a conjecture for the relationship between velocity, trip time, starting location, and ending location.

Episode Supports

Students’ Conceptual Challenges

At different points in the video, the pair of students seem to be on the verge of realizing that the distance traveled is the product of time and velocity. However, they use phrases such as “whatever the trip time is and the velocity is, it’s like the distance” [4:23] and “[the distance] would be whatever the trip time is and the velocity is…” [5:25]. It can be challenging to productively discuss quantities and relationships between them.

Focus Questions

For use in a classroom, pause the video and ask these questions:

  1. [Pause the video at 3:00] ET seems to connect the distance covered by the scooter rider Hector, which was 40 meters, to the product of the time spent riding the scooter (10 seconds) and the velocity (4 meters per second). Ask your students what they think about this claim? Is ET correct? Why or why not?
  2. [Pause the video at 3:41] Haleemah and ET have decided to start a scooter ride at a distance of 0 meters from his house. Hector will ride for 8 seconds and ride with a velocity of -7 meters per second. Prompt your students to predict where Hector’s location at the end of his ride. Ask them to either test ET’s hypothesis or come up with their own method for making a prediction.

Supporting Dialogue

After creating and watching two scooter rides, Haleemah says “It really does seem like, you know, whatever the trip time is and the velocity is, it’s like the distance.” [4:23]. Pose the following questions to your students: “What do you think Haleemah is figuring out about this context? Do you think she is right? Why or why not?” Encourage them to support their answers with evidence from the video.