ANS: An "Open Book Examination" is that in which students are allowed to refer to either class notes and summaries or memory aid, textbook, or other approved material while answering questions.

It basically tests the ability to find and use the information for problem-solving and to deliver well-structured and well-presented arguments and solutions. 

Open Book Exam Questions usually require applying knowledge, they may be essay-style questions or involve problem-solving or delivering solutions.