Interactive Graphing

Great site that allows you to graph points and lines.

http://www.mathsisfun.com/data/cartesian-coordinates-interactive.html

Here is one for quadratics...

http://www.mathwarehouse.com/quadratic/parabola/interactive-parabola.php

Here is an on-line graphing calculator.

https://www.desmos.com/calculator

Here is one that does lines, connect points, and scatter plots.

http://www.shodor.org/interactivate/activities/OrderedSimplePlot/

UPDATE: 4/17/2015

Here is an app that you can add to Chromebook. Go to the Chromebook Apps Store and search "Graph.tk." This app allows you to enter the formula, and it creates the graph.