Throw away your graphing calculators! Desmos offers a free graphing calculator that is very easy to use and they regularly add new features. In terms of ease of use and features, there isn't another calculator that compares.
I discovered the graphing calculator shortly after it was launched in 2013. I eagerly showed friends, family, and colleagues what could be done with it. Here is the first graph I created with it (and 2 derivations):
Can you generate the graph I made? Post in the comments if you can.
Desmos has a library of activities for teachers or you can create your own for your students here. My personal favorite are the Marbleslides activities. My students have explored these for hours of fun.
In subsequent posts I will highlight a few of the ways in which I use Desmos with my students.