Sorry to disagree with you, Joseph, but it is possible in Moodle 1.9.
First, as Admin, you have to override permissions for the course concerned so that Guests can attempt and preview Quizzes.
Then there are two ways to let Guests do the Quiz:
- Give them a direct link somewhere like this: Eastenders.
- Tell Guests on the course page something like: "You can do the Quiz activities if you click on Preview (Example: Grammar Activities).
I'm sure that among the 231 results I've already explained this.
I've been doing it for years.
It does depend, though, what you mean by "do". With my workaround there'll be no meaningful results in the Gradebook but Guest do see their results as they work through. No idea what would happen if 1000 Guests were working simultaneously.
Cheers,
Glenys