This is a simple applet to help students under the vertex of a quadratic function.
The idea is that they
* Input a quadratic function (the show vertex checkbox will automatically be false)
* Click and drag A (or click on A and then use arrow keys) until they get a minimum (or maximum) y-value and then
* Click the "Show Vertex" to check their answer.
Note: I despise using "completing the square" for this and wait until my kids have derivatives to make them find the vertex algebraically.
