I'm wrapping up 3 weeks on relativity in my freshman calc-based physics course at the community college where I teach. At my final meeting, I want to spend most of the time having the students break up into their lab groups and discuss certain specific misconceptions, questions, and confusions about relativity. Each group will have certain questions that are assigned to them. I'll mostly just walk around the room and listen, maybe giving corrections or help if they're stuck or messing up. At the end, they'll present their answers to the rest of the class. I've been looking over PF's relativity and cosmology FAQ lists, etc., for possible questions to assign, and have come up with the following that seemed to be reasonable ones to expect students at this level to be able to attack: How can light have momentum if it has zero mass? Accelerate a baseball to ultrarelativistic speeds. Does it become a black hole? What does the universe look like in a frame of reference moving at c? Where did the Big Bang happen? I would like to at least double the length of this list. Does anyone have any others to add? I'm hoping that such a list would be helpful to other people besides me. To give an idea of the level of questions that might work, here's what we've done this semester: -- My students started by reading Gardner's Relativity Simply Explained, which covers both SR and GR at a popularized level. I just assigned them to read one chapter for each meeting, and quizzed them to make sure they did the reading, but we didn't discuss any of it in class. After that, I did SR from scratch at a slightly more mathematical level, using the pedagogical approach typified by Takeuchi and Mermin, i.e., we don't write down a lot of equations, but mostly just draw spacetime diagrams and represent Lorentz transformations as distortions of the Cartesian graph-paper grid overlaid on the space of events. The book is online here: http://lightandmatter.com/area1sn.html (ch. 7). What they know about dynamics is basically the equations p=mγv and E=mγ (in natural units), plus whatever they've soaked up informally from Gardner. I have also introduced them briefly to the energy-momentum four-vector and the relation m2=E2-p2. They know Maxwell's equations and have been informally introduced to electromagnetic waves, but we haven't actually gone into EM waves as solutions of Maxwell's equations in detail. They have been introduced briefly to the light cone, but not the spacetime interval. Thanks in advance for any suggestions!