In this paper, we investigate the given ambient lighting conditions in today's schools. On the example of Oulu University Teacher Training School, the classroom quality in terms of the available amount of ambient lighting is analysed. In particular, attention is paid to the available illuminance of the pupils' desks. Commonly, light is produced artificially by light sources installed on the classroom's ceiling and obtained from the outside through windows. However, due to the use of digital blackboards, window blinds are often closed and lights are often switched off, thereby, reducing the available light in the classroom significantly. Furthermore, our results reveal that each pupil's desk receives a different light intensity. It is worth noting that low levels of ambient lighting can result into a degradation of learning performances and, therefore, requiring pupils more time solve different types of activities assigned by the teacher.