On the other hand, all school teachers pay attention to check that their students are focusing. They use neural networks for that (their own neural networks) that are very well trained in detecting lack of focus from body movements, facial expressions, chatter, etc. A device that actually allows more easily to detect focus is scary if it's used improperly, that is, if focus is required all the time. But if used in a balanced way allowing for prolonged periods of relax and "mind wandering" it might actually be helpful.