Why not give a test on Monday, and then give another test later that day? I bet they would be surprised by a second test on the same day.
True, there's nothing saying there won't be two tests.
Rather than solve this, I was hoping people'd take a look at the linked explanation. When phrased more carefully, it becomes a whole bunch of nested paradoxes, the resolution of which contains valuable lessons on how words can trick people. It covers some LW material along the way, such as Moore's Paradox.
An Open Thread: a place for things foolishly April, and other assorted discussions.
This thread is for the discussion of Less Wrong topics that have not appeared in recent posts. If a discussion gets unwieldy, celebrate by turning it into a top-level post.
Update: Tom McCabe has created a sub-Reddit to use for assorted discussions instead of relying on open threads. Go there for the sub-Reddit and discussion about it, and go here to vote on the idea.