More happy discoveries with the excellent Desmos Graphing Calculator ….
Points of Interest
Click on the image of the cubic graph below and select points on the graph such as axes intercepts and stationary points.
These can be entered (as can coordinates) using square brackets; the domain can be edited.
The sliders feature can be used too, for example try this graph of a circle given in terms of its parametric equations. Selecting the slider allows editing, for example as here it is possible to set the interval so that only integer values are possible.
See also Pretty Graphs, Desmos Delights, Graphing Inequalities and these posts on my blog for students: Explore Straight Lines and Explore Graphs.