A display question is a type of question where the questioner already knows the answer. Display questions are used in language education in order to elicit language practice. They are contrasted with referential questions, questions for which the answer is not yet known. The use of referential questions is generally preferred to the use of display questions in communicative language teaching.
Example
Richards and Schmidt give the following example:
Q: Is this a book? A: Yes, it's a book.References
Display question Wikipedia(Text) CC BY-SA