Fall and Rise of a D2O Ice Cube in Liquid H2O

In this section of Resonance, we invite readers to pose questions likely to be raised in a classroom situation. We may suggest strategies for dealing with them, or invite responses, or both. "Classroom" is equally a forum for raising broader issues and sharing personal experiences and viewpoints on matters related to teaching and learning science. The demonstration described in this article is to show that while H2O ice floats in water, D2O ice sinks in water, proving the higher density of 'heavy water'. This experiment can be done in a classroom or in an auditoriam.