App Engine's going read-only for maintenance for up to an hour on Tuesday, at 8PM Eastern time (midnight UTC). You won't be able to practice while it's down, but this time I should have fixed it to tell you that, at last!

The maintenance window isn't exact, so feel free to study until it kicks you off. Sometimes they start late or finish early.

Same deal on Wednesday, April 20. I'll bump this thread before then to remind.

Doing this again tomorrow night, too, same time. I might have worked out a better way to notify you before you start trying to practice by then, or maybe not.