Lack of concentration in class can be caused by the following reasons: interference from the external environment; lack of interest in learning; fatigue; and ADHD. 1. External environmental interference: for example, when studying, the external environment is too noisy will affect the mental concentration, from the sound of car horns, as small as the sound of whispering may be, if it is because of these external factors caused by distraction, then the best way is to cultivate their own anti-interference ability. 2. Lack of interest in learning: There is no way to concentrate if you are not interested in something. Therefore, in order to concentrate, you need to cultivate your own interest. 3. Fatigue: Fatigue can also lead to a lack of concentration. Therefore, in order to concentrate, you can take a proper rest, and you can achieve better results when you have a good rest. 4. Hyperactivity disorder (ADHD): It is also possible that children do not concentrate in class because they have ADHD, so they are not able to concentrate. There are many reasons for not concentrating in class, if necessary, you can go to the regular hospital.