At this workshop the participants get to try encrypting and decrypting messages and learn more about various encryption methods. Mathematics researchers are often best suited to lead this type of workshop.
Target group: Works for a broad target group.
Preparations: Find leaders for the workshop, decide on a venue and time. Organise the necessary materials. Market the activity.
Challenges: Coming up with tasks to keep the participants interested.
Benefits: No expensive materials are needed, fairly easy to arrange.