the criteria for grades will depend on each individual hospital. although i believe you are inquiring about an externship. externships are offered during the summer at some hospitals and year round at others. internships are usually 12-16 weeks training when you're done with nursing school and become a graduate nurse. my best advice to you is to contact whichever hospital you are interested in, and speak with hr about their externship program. they will be able to answer all of your questions for that specific facility.