why did albert felt miserable when he left school that afternoon/

According to Einstein's biographer, Patric Pringle, Einstein hated to go to school. Since Einstein was very rational in nature, he found it difficult to accept and adjust to a system of imparting education, which to him was useless. Moreover, most teachers reprimanded Einstein, because they considered to be rebellious in nature. However, Einstein was getting used to the fact that his days in school would be difficult. However, he felt miserable not because he had a bad day in school, but because he had to go back to the same school the following day. This situation helps us understand the rational nature of Einstein and also feel sorry for his helplessness.