Computers are down; what's in your bag of tricks for teaching CS when they can't get on a computer?
There are lots of great activities at CS Unplugged that do not require a computer. Excellent activities in their own right, you don't have to wait for the days when systems are out. Well worth exploring these resources.

This resource is provided by the Computer Science Department at the University of Canterbury, New Zealand, and shared under Creative Commons BY-NC-SA 4.0 licence.