This small group activity is designed to help upper division undergraduate students analyze relativity paradoxes. Students work in small groups and use spacetime diagrams to analyze relativity paradoxes sometimes not considered, such as the "manhole-cover" paradox. The whole class wrap-up discussion includes group presentations, allowing students to reach consensus in resolving each paradox as well as observe some of the interesting properties of special relativity.

This material is part of the Paradigms in Physics project at Oregon State University. This work promotes the use of active student learning in upper division physics courses. Both learning materials and learning strategies are provided to help both students and instructors.