No matter if Mr. How just learned English last month, or if he had known it all his life, you need to change the highlighted comma to a question mark because he is asking a question.
“Daniel, where’s your book#FF4000 ">,” Mr. How asked in his high pitched Chinese accent.
Similies are comparing to things of different kinds using like or as. I think that a guy trying to sleep wouldn't be bored. You could say he was trying to sleep, or create a new simile like "bored as a American football player sitting through a lecture on collage-level quantum physics and it's application to cooking."
Daniel Herman sat in maths class#BF4040 "> bored as a guy trying to sleep.
I'm sure you could find the other things if you edited, because they are mostly grammatical.
