The orbital motion of Jupiterʼs Galilean satellites can be studied using the medium-sized telescopes commonly found in college or school observatories. In this paper we show how it is possible to deduce the parameters of their orbits around Jupiter using a small number of well-planed observations. This allows the instructor to propose a complete student activity that involves planning an observation, the observation itself, processing and analysing the images, and deduction of relevant magnitudes.