Exponentials Lesson 4 Episode 1 (Teachers)

Making Sense

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The students use the timeline they made in the last lesson to determine the height of the beanstalk on Day 12.

Episode Supports

Students’ Conceptual Challenges

Precision with language can often pose challenges for students. In this episode, Josh refers to the height of the beanstalk as “three to the power of the day” [2:00], which seems to have mathematical meaning for both Josh and Arobindo. Even so, the precise mathematical idea that needs to be understood is that the exponent should represent the number of days the beanstalk has been growing since Day 0, so it would be more appropriate to say the height is “three to the power of the number of days it has been growing.” 

Focus Questions

For use in a classroom, pause the video and ask this question:

Pause the video at 0:36] Can you determine the height of the beanstalk after 12 days? Create a timeline that illustrates this situation. When you’re finished, watch the video through [1:34] and compare your work and timelines with those of Josh and Arobindo.

Supporting Dialogue

Arobindo and Josh claim that the expression 312 represents the height of the beanstalk after 12 days. Josh argues that this expression is correct because the “height is three to the power of the day” [2:22]. Ask your students to discuss what they think Josh means by “the day”?