Six groups of 2 to 4 students conduct an open-ended inquiry into factors affecting the growth of an E. coli population. Students must collect data over a 3-hour period, taking a measurement every 15 minutes. The E. coli population is used as a model to show logistic growth. Students discuss what might limit the growth of the population and design experiments to investigate the effects of altering different factors, such as nutrition or accumulation of waste products. Turbidity data can be interpreted to determine if the factor affects growth rate, carrying capacity, or both. If time permits, students can refine experiments, repeat them, or design additional experiments to look at more factors. This is not a "cookbook" laboratory procedure; it is excellent for advanced classes, AP® classes, or undergraduate laboratory courses.