Desmos, a free online graphing calculator that I reviewed in June, recently added a handful of new options that should be appealing to mathematics instructors and students. The new features enable better handling of strict inequalities, polar inequalities, internalization, slider bars, and graph tracing. The video below provides an overview of the Desmos graphing calculator.
Applications for Education
Desmos could be the replacement for those expensive TI calculators that sometimes disappear from schools. I like that you can share your work via shortened Bit.ly links. I could see teachers modeling with Desmos and sharing. I could also see students sharing to do collaborative problem solving.