Google is doing some maintenance on App Engine, supposedly starting now (noon Eastern) and lasting up to an hour. We've added some checks that should fix the site enough so that read-only parts work, but the rest will show a "disabled" page. We'll see how well it works shortly.

Thanks for your patience.

Downtime was completed on time and things should be good to go, but any Flash sessions you practiced with when it was going on were probably messed up, so you'd need to reload. But if you're reading this, you're probably not also still on the practice page, so that's good.

Nick, it's still not working for me. I'm getting "Server Error" messages, and my progress isn't saving.

working here (didn't work earlier, Server Error). took a while to load, or at least seemed that way, this time.

Just reloaded and it's working fine.