The present research is aimed at analyzing the professional gestures of a museum educator in a specific situation: the demonstration of the Foucault Pendulum in the Arts et Metiers Museum in Paris. What professional gestures can give him the ability to present this object to a mixed audience in a museum space open to visitor circulation? How does he manage to capture the attention of his audience and make scientific knowledge accessible? Does the educator work like a teacher? Such are the questions that the research team had in mind and which allowed them to conceive the scientific museum educator's action from the point of view of professional gestures.