HOW DO STUDENTS USE SPATIAL REASONING TO MAKE SENSE OF DEMONSTRATIONS IN ROTATING TANKS?

Rotating tanks are a popular teaching tool in meteorology and oceanography where instructors use them to model fundamental concepts that emphasize geophysical fluid dynamics. Rotating tanks also provide popular outreach demonstrations for elementary school to university level students and can range from tabletop models run with a LEGO motor to high quality systems made of a 3-foot diameter rotating tank on a powerful motor. We used a large rotating tank to investigate student use of spatial reasoning while making sense of fluid behavior demonstrations. Rotating tanks can model vortices, gyres, and convection, along with more explicit phenomena such as Ekman spirals, Taylor columns, and baroclinic instability. Our pilot work, however, showed that students struggle making sense of basic demonstrations, so we began with simple models of fluids spinning from rest and in solid body rotation. We worked with 26 students in individual semi-structured, discursive interviews with students observing and predicting the motion of plastic fish in water spun from rest and the behavior of dye in water in solid body rotation. We combined think-aloud methods with interactive discussion to prompt student thinking, encourage sense-making, and to make spatial reasoning processes visible. We video recorded and transcribed each session and collected predictive and post-observation sketches. To analyze the data, we used an inductive and comparative method that sought to characterize student spatial reasoning. Our findings show that spinning fluid behavior is highly unintuitive for students. The students had difficulty articulating what they saw, describing relative motion, and relating observations to everyday experiences. No student correctly predicted the motion of water in solid body rotation. Our work is addressing questions such as “Do misconceptions originate with fluid behavior, spinning objects, or both?” “Are students struggling with working in multiple frames of reference?” and “On what experiences are students basing their predictions?” Although the results suggest caution in assuming rotating tank demonstrations are advancing student understanding of the processes they intend to support, we encourage further work to investigate effective use of these demonstrations in fluid-Earth science courses.