At IATEFL 2018 in Brighton, I presented on the benefits of using mysteries in class, some of the difficulties mysteries present, and three methods for mitigating those difficulties while reaping the benefits. Here is my slide show and the handouts.
Crime Scene Picture Mystery: Reduce the language students have to process with a mystery activity that relies on visual clues. Students will still produce plenty of language.
Mystery Analyzing Worksheet: A graphic organizer students can use while they read is a great way to help them analyze clues and suspects.
Empty Bank:A short mystery activity where students are presented information one clue at a time to reduce the amount of processing they have to do at a time.
The Weird Break-In: Another short mystery activity.