No captions Captions Stop the video above first if it is playing.
No captions Captions Stop the video above first if it is playing.
Sasha and Keoni generalize their “short cut” method from Episode 3 by solving x = √(4y) for y.
Episode Supports
Students’ Conceptual Challenges
Students often find tasks like the following challenging: “Solve x = √(4y) for y”. In part, that’s because their conception of solving the equation is to produce a numerical value for y.
By generalizing their method for solving for y when x takes on different values [see 0:42 – 1:27], Sasha and Keoni are able to rewrite the equation successfully [1:57-2:12].
Focus Questions
For use in a classroom, pause the video and ask these questions:
1. [Pause video at 1:27]. Summarize Sasha and Keoni’s method for solving x = √(4y) for y when x is known.
2. [Pause video at 1:50]. Sasha just said, “What?” What is different about this request to solve for y?
Supporting Dialogue
Ask students to relate this mathematics to other math from school by asking:
Where else in our math class have you been asked to solve an equation with two variables for one of the variables (like Sasha and Keoni rewrote x = √(4y) in terms of y)?
Math Extensions
1. Sometimes equations can have more than one variable. Solve the equation below for x. Solve the equation for y. Which is easier?
x2 + 25y2 = 100
2. Are there some values of (x, y) that you can see will or will not satisfy the equation without solving for x or y? What are your strategies?
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