ABSTRACT
“OK, there you go. It’s sensitive!” Jay pushes up on the rubber sheeting of his newly completed “Australian” Cartesian diver system (CDS), in which the entire system is inverted. To operate this system, one pushes up on the rubber sheeting while the diver floats at the top (what used to be the bottom) of the inverted test tube. As in the regular CDS, this causes the water to enter the diver, compress the air therein, and the diver begins to sink. Exploration of the Australian CDS marks the beginning of the students’ second cycle of investigation, in which they typically explore the same phenomena in a different context in order to refine their understanding of it. Jay holds his system up for Laura, who is leaning over his desk to watch Jay and Ned working, to examine.
