# Parabolas Lesson 4 Episode 5 (Teachers)

### Reflecting

Keoni and Sasha compare the equations x = √(4y) and y = x2/4.

### Episode Supports Focus Questions

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

1. [Pause video at 2:01]. What makes an equation easy to use?

2. [Pause video at 3:21]. Which equation would you use to find the b-value when the y-value is 1.5? Why?

Supporting Dialogue

Ask students to reflect on the difference between expressions and equations by asking:

• Is there a difference between y = x2/4  and  x = √(4y)?

Create the opportunity for productive disagreement by asking:

• How many of you think that there is a difference? How many think that they are the same? Can I have someone defend how they are the same? What about someone to defend how they are different?

Math Extensions

Physics uses mathematical equations to express known properties and theories.

1. Isaac Newton derived a universal law of gravitation. The equation is given below. F stands for the force between two objects. G is the gravitational constant. m1 is the mass of the first object. m2 is the mass of the second constant. d is the distance between the two objects. Rewrite the equation be solving for d. How would this form of the equation be helpful?

F = G(m1m2)/d2

2. Now solve the equation for m1. How would this form of the equation be helpful?