No output from Jupyter notebook

I am taking DLS Course 1 on Coursera. Today I opened my lab file and evaluating input cells that should give an output does not give any output. I have tried restarting the kernel and using Firefox instead of Chrome. It is as though there were no kernel there. Note this should be running on the Coursera server, not my laptop (if I understand correctly).

Yes, that’s correct: all actual execution happens “in the cloud”, not on your laptop. So as you say, it sounds like the “kernel” is not working. The first question is whether this is your first time trying this or you have been successful running the notebooks earlier. If this has literally never worked for you, then you may have an “IT” problem, e.g. some AV software, ad blocker, proxy, firewall, yadda yadda is blocking the connection to the kernel in the cloud. If it used to work, but suddenly doesn’t, then it’s more likely to be “bad weather” in the cloud. Note that there’s a little circle in the header of the notebook that is solid when the kernel is running, so that you have a visual indication of whether it is busy or not. Watching that may give a bit more information on what is happening …