This article describes an interdisciplinary unit in which students explore biological "ice nucleation"--by particles that cause water to freeze at temperatures above -38°C--through the lens of the microbial ice nucleator "Pseudomonas syringae." Such This activity, which aligns with the "Next Generation Science Standards", exposes students to the global water cycle, highlighting the importance of critical and ethical thinking at the intersection of biology and engineering. Furthermore, the activity is designed to: (1) introduce students to principles of ice nucleation and allow them to recognize the diversity of ice-nucleating particles; (2) allow students to recognize how interdisciplinary research can address complex problems across multiple fields of study, using ice nucleation and its relationship to atmospheric processes as an example; (3) have students consider principles of experimental design, including the formulation of testable hypotheses and the inclusion of appropriate positive and negative controls in developing an ice nucleation test; (4) have students design and conduct an ice nucleation experiment with known and unknown samples of undetermined ice nucleation activity; and (5) highlight connections between systems of different scale such as microbiology (ice nucleation) and the global water cycle (bioprecipitation).