There are two main reasons why I believe that arts are very useful in not only school but also daily life.
The formatting of this sentence should have been divided into 2. Rather than saying there are 2 main reasons, present the reasons individually in a manner that provides an overview of the topics within the school and personal settings. Such a presentation would have added clarity and coherence to the succeeding paragraphs. That said, I must commend the writer for the creative prompt restatement.
Do not go beyond 2 reasons.The prompt isa standard 4 paragraph presentation, with a 2 paragraph reasoning allotment. It is the entry of the 3rd reason, which could have been easily merged with the second paragraph that led to the under discussed second paragraph. Without this error ,the essay would have been in a better place for a higher score since the essay only has negligible errors.
P.S. Aim for a 2 sentence conclusion as required next time.