Black holes are mysterious objects in the Universe. What are they? How do scientists discover them? In this Teen Astronomy Cafe — To Go! Instant Pack, students learn what black holes are and how astronomers use light to measure distances. Students then analyze photon flux plots and compute light travel distances to determine the duration and brightness of a flare from black hole and the energy it emits. This activity is conducted in a Python Notebook, a web-based interactive computational environment that contains code, text, and plots.