In this study, the learning of DC-circuit phenomena in a small group in the 3rd grade (9-year-olds) of a comprehensive school is scrutinised. The focus of the study is on the progressive nature of learning sciences, and especially on its active and spontaneous components. Learning in a small group is examined from the standpoint of pupil's talk. The article explores the small group's learning process for the basic components of DC-circuits, especially bulbs. This process is treated from the standpoint of developing the conception of "the brightness of the bulbs". In this study it is shown that even in the case of abstract subject matter, a small group can be a fruitful learning environment, where active and spontaneous learning can take place.