Hi. I am developing a role-playing simulation for middle school students who are on board a simulated spacecraft orbiting Mars. The spacecraft is a physical mock-up. Inside the spacecraft they conduct experiments inside a glovebox. For one of the activities, I would like the students to drip some substance on a rock and for the rock to fizzle or bubble. Ideally, the substance would not be a substance that is unsafe. What do you recommend for the drip solution and for the rock?
