According to Robert's behavior, he is most likely to be diagnosed with attention-deficit/hyperactivity disorder.
Attention-deficit/hyperactivity disorder or ADHD is a brain disorder characterized by problems paying attention and hyperactivity-impulsivity that makes it difficult for the person to control his o her behavior.
In this case, Robert seems to have ADHD since he can't focus in class and he is extremely active and impulsive, which means that he presents the classic symptoms of someone who has this disorder.
Moreover, it is common in children who are diagnosed with ADHD to have problems paying attention or stay calm at school, which results in poor school performance. It can also affect other life areas.
