For Your Mathematicians: Desmos: A Browser-Based Advanced Graphing Calculator
Link: Desmos: A Browser-Based Advanced Graphing Calculator
Well worth a look. I will be letting maths teachers at my school know about this site.
Although our content platform is still in private beta, you can get a taste of what's to come with our free browser-based calculator! Forged from the Desmos math engine, this is the best browser-based calculator on the web.