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 use their equation (which they call the “short-cut way”) to find the y-value of 3 points: when the x-value is 5, 10 and 437.
Episode Supports
Focus Questions
For use in a classroom, pause the video and ask these questions:
1. [Pause video at 1:03]. Without using a calculator, how can you determine the value of 25/4?
2. [Pause video at 1:50]. Sasha just wrote that y = 25. What information does that give you about the parabola?
Supporting Dialogue
Invite a reluctant or shy student to suggest an x-value on the parabola (just like Keoni suggested x = 437). This is an accessible entry point for students who find contributing to class discussion challenging. Then ask the class to find the y-value for that point by using the equation x = √(4y).
Create an opportunity for productive disagreement by asking students if there is an x-value for which there will be no y-value on the parabola. Some students may think the parabola “ends” at about x = 8.5; others may not conceive of x-values other than whole numbers; and some may understand that there are infinitely many points on the parabola and that x can be any number.
Math Extensions
1. What is the y–value of the point on the parabola with the x-value of –7.1?
2. What is the y–value of the point on the parabola with the x-value of √11?
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