how can you show professionalism in school?

You can show professionalism in school by getting your work done in class as well as getting your homework done on time.  Always participate when a teacher asks question, it shows you are paying attention to what he/she is saying. Don't be late to class, it will lower your grades and show you don't care about the class.

how can you be prepare for a job interview?

the best ways to prepare for a job interview is to be sure to be on time, it shows your interested in the job. Have all your paper work and resume ready before getting there, it shows professionalism. Wear a neat attire, dress to impress. It's always good to show the best of you when you going for a job interview, in order to get the job you need to impress them and show them you're the right to be hired for the job.