A regular random rotation or a daily display of multiple quizzes from which to choose would be great. I manually rotate them periodically (when a country has multiple decent quizzes), but unless a quiz proves to be really unpopular when the bus visits (that is, its ranking drops dramatically that week), I leave them in for at least a couple of cycles. If instead of a single quiz on the list for each country there were more to be selected from (currently there are nine countries for which I haven't got any second possibility listed), it could offer more variety. And if it could be flexible enough to have a different number of quizzes for each country, even better - there are a couple of countries for which we have more than three really good quizzes, and they cannot all be there at once when it is a single list.
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(Editor in Humanities, Religion, Literature and For Children)
That's all, folks!