Hackpad for GCSE computer science
I have been experimenting again with Hackpad recently. Since I last looked Hackpad seems to have been acquired by DropBox. But I note that Hackpad has some useful features for teachers of computer science - not least that any code you past in has line numbers by it.
Here is a little bit of code I'm going to get my GCSE computer scientists to improve so that you can see what it looks like: