The pendulum has a great relevance in physics and it has been explored in educational papers from many theoretical or experimental points of view (see, for example, Refs. 1-12 and references therein). Here a method for the measurement of the gravitational acceleration with a large number of trials is presented; we assume that the systematic errors can be neglected. The experiment has been carried out with 250 first-year university students (students not enrolled in physics). Although the pendulum can be considered as a standard part of the introductory courses in physics laboratory, the approach described here allows students to handle various aspects of data analysis.