1. Anxiety and nervousness: Shaking one's legs may be a natural reaction when one faces pressure or nervousness. They may want to shake their legs to release their nervousness and ease their inner anxiety.
2. Boredom and impatience: If the course content is not attractive or challenging to someone, they may feel bored or impatient. Shaking your legs may be a way to seek excitement or divert your attention.
3. Habit and self-regulation: Some people may have developed the habit of shaking their legs, whether in class or in other environments. Shaking their legs may be a way for them to adjust themselves and help them concentrate or relax.
4. Lack of consciousness: Some people may not realize that they are shaking their legs, or they may not think it is a bad behavior. They may not realize the influence of shaking their legs on others, or they may not realize that shaking their legs will interfere with their study.
5. Social signal: Shaking your legs may also be a social signal, which is used to convey some information or establish contact with others. For example, shaking your legs may be a way to express dissatisfaction, impatience or disagreement.
It should be noted that the reasons for shaking legs vary from person to person, and the above are just some possible explanations. For some people, shaking your legs may be just an unconscious behavior, while for others, it may be a conscious choice. In any case, if shaking your legs interferes with others' study or causes discomfort, you'd better try to avoid it or try to find other ways to deal with anxiety, boredom or other emotions.