I am starting to focus in to think about what I want to do with my classes during the first week of school. For Calculus, I think the choice is obvious. I should start them off by playing with Function Carnival, over at Desmos.com!! (For those of you who, like I, did not attend Twitter Math Camp and have missed the demo / all the blogosphere buzz, you should sign up for an account at teacher.desmos.com to play with their interactive applets immediately. The interface is thoughtful and it allows you to collect data regarding what your students are creating as graphs and how they analyze other people's errors, and you can use it at the start of a unit to build understanding from recognizing and addressing misconceptions.) I will be starting them off easy, on Day 1, by playing with the regular algebra version to warm up. And then, on Day 2, plunge them right into predicting and testing velocity function graphs in the Function Carnival, in order to jump-start their interest in thinking about rates of change.
To reiterate things that others have said, I really like the ability to both toggle through individual students' responses and to look at the whole class's responses at once. To start with this activity at the very beginning of the year can help me to set the tone that it is okay to experiment and to make mistakes, because that is how we learn math.
Yay Desmos! This is really a fantastic tool that incorporates real mathematical instruction, not by replacing the whole-group experience but to reinforce it by giving each student a structured think-time before the whole-group discussion. I really hope that this is the future of digital instruction!