Update – note that all the Desmos posts now have their own page.

Checking Twitter this morning I noticed Richard Byrne’s post (Free technology for Teachers) on the new graphing calculator from Desmos.

This is easy to use and the ability to set up a page then save the url means teachers can set up pages for students to explore families of graphs.

(See Explore Graphs.)

Variables can easily be changed to see the effect on the graph, for example click on a, b or c to change the value of the variable and note  the change in the parabola.

There are several examples already set up, for example one could choose the vertex form for a parabola from the examples list.

Inequalities are handled very well, unlike many free graph plotters it is easy to plot lines of the form x=k.

It is possible to show several graphs on the same diagram, so transformations could easily be explored.

Wondering if what we see now will remain free I sent this enquiry to Desmos who replied very swiftly and courteously that it would indeed (and more to come!)