I've created a 20 question quiz on the plot of Beowulf. It was designed to assess whether or not students read the story and whether or not they comprehended key points. It was also designed so that students reading a synopsis prior to close readings of excerpts could be assessed on their comprehension of the overview. Questions cover characters and major conflicts.
The quiz is just $1, and comes with an answer key. If you teach British Literature, you should check it out.