Made with Code, a website geared to introducing girls to the wonder of computer science, has a fun holiday online activity called Project Lights.
Using a simple Scratch-style block building mechanism, users create a Christmas tree light display. Once completed, the program will be queued to run at a specific date/time, presumably if you were in the DC are you could go and see your results live.
They also include a downloadable GIF file and the ability to share your work on social media. While not earth shattering computer science, and the programming is rudimentary, this would be a fun introductory project for younger children.