A recent development of phenomenography, variation theory, is illustrated using a video recorded case of learning. From a variation theory perspective, to learn is to be aware of critical aspects of what is learned. The way we experience or understand something depends on what aspects we are aware of and can discern simultaneously. The possibility for the learner to discern and focus on these aspects is critical for learning. But we can only discern an aspect if we experience a variation in that aspect. Thus the possibility of experiencing variation in critical aspects is a necessary condition for learning. Variation theory is proposed to be a powerful means for describing and revealing conditions critical for learning in a pedagogical setting. (Contains 2 figures.)