So sorry to hear that you are having a problem with your feed, the issue might be with feedburner having a problem communicating with your feed while the upgrade process was on.
I have discontinued support for the plugin, however I cannot let anyone be stuck with it, so here goes.
Though this is the first time I saw this, here is what you can do to troubleshoot;
1. Disable the Feedburner Feedsmith plugin (which I think you are using) and access your feeds through http://beyond-school.org/feed and let me know if you are having problems there too, if not enable it back and follow the feedburner problem steps.
Feedburner problem
1. Login to your feedburner account and go to the feeds for this site.
2. In the top you will see a tab troubleshootize, in the left hand side you will see a link for Feedmedic, click on it and see if the feed if having any problems, if yes use the steps provided to trouble shoot the problem.
3. If no probs exist click on the troubleshootize again and scroll to the middle of the page, you will see a button called "Resync Now", click on that and wait for 10-20 mins and check if your feed is working.
If these steps do not work and you are not able to find a solution for about 60 minutes feel free to email me on this ID.
Cheers
Keith