Read the following text and answer the question.

I have a brother. He is a diligent worker. He always wakes up early in the morning and prepares everything for his work. He always takes me to school first before going to the campus where he teaches. At night, he seldom watches television. Instead, he prepares materials to teach. Occasionally, he also gives me good materials to study. 

From the description above, what is the writer's brother's profession?