Desmos just released their newest set of activities on Tuesday, aptly named "Marbleslides". I decided to use the last day before Christmas vacation to let my algebra 2 students give the Parabola challenges a try. I forced students to work as pairs instead of having them work independently. I have found that my room is very quiet when students work on Desmos activities by themselves. I wanted more collaboration and thinking out loud; I wanted more noise.
It appears Desmos hit a home run with their latest release. More than once I had students arguing about whose turn it was to run the controls. Many students left class with a new addiction.