Equations of a parabola in vertex form

Use the sliders to change the graph of the parabola.
Write the equation of your new graph in vertex form.
Use the check box to check your equation.
(Be sure to have some parabolas open up and some open down.)

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What happens to the graph when value of a is negative?
What happens to the graph when -1< a < 1?
What happens to the graph when a > 1?
What happens to the graph when a < -1?
How does the point (h, k) relate to the parabola?

Linda Johnson, Created with GeoGebra