The study of energy metabolism is fundamental in multiple disciplines, such as biochemistry, bioengineering, biomedicine, etc. Traditionally, in high school and college level courses, students are taught energy metabolism (glycolysis, Krebs cycle, and oxidative phosphorylation) through diagrams of metabolic pathways that depict the transformation of carbohydrates. In this laboratory teaching experiment, we conducted basic respirometry experiments that allowed students to collect, process, and interpret data on mitochondrial metabolism; their challenge was to calculate the number of ATP molecules that mitochondria inside a cell can synthesize per second. The goal was to introduce basic concepts of bioenergetics and metabolism. The pedagogical objective was to assess whether understanding how a metabolic flux is experimentally evaluated and processing the resulting data could enhance students' knowledge of oxidative phosphorylation and its relevance to the cell. The models used in the respirometry experiments include a human breast cancer cell line, a nonmalignant mouse myoblast cell line, and "Trypanosoma cruzi," a homoflagellate parasite that causes Chagas disease and has the peculiarity of having a single mitochondrion.