Desmos

Desmos is a free graphing website that offers so much more than just graphing. Users can create elegant cartesian or polar graphs that can include parameters with sliders. Images can be inserted easily, offering ample opportunities to explore transformations and curve-fitting, among other things. Text and table elements can also be inserted, and there are a variety of example graphs available from linear and trig functions to Calculus concepts. Work can be saved to Google Drive, and the site offers support for multiple languages. Desmos is also available as a free app for the iPad.

Another great resource from Desmos is teacher.desmos.com, which includes great interactive classroom exploration activities. Students join your class using a code at student.desmos.com. As students interact with and explore the activity, you can see the work from all of your students on the teacher dashboard.